Realistically, you're not going to cruise CHEAPLY any time of year, and especially not in July. Prices are higher then because kids are out of school. Here are random tips that'll save money:
Pick out your dates, keep an eye on the website, and book as soon as the dates open up. Watch the site, and IF the prices go dow, you call in for a "price match". If they go up, you're already locked into the lower price. Dates tend to open up about 18 months in advance. You have everything to gain and nothing to lose by booking as soon as the dates come open.
The best cabins -- that is, the ones that offer the best bang for the buck -- go within the first week or so. For example, Disney has a couple cabins that have windows partially obscured by lifeboats. Because they're not really good, complete windows, they sell these as insides; but you're still getting natural light. The balcony rooms allll the way to the back of
Royal Caribbean have room-sized balconies, yet they sell for the same price as the "why-bother? balconies" on the side of the ship. Royal Caribbean's Family Promenade rooms, too, go fast. To really get the most for your money, you have to do your research, know what's best for your family, and be prepared to book well in advance.
Booking 4 people in a cabin is
usually a money-saver. The first two people pay a higher charge, and the second two can go for less money. Not all cabins hold 4 people, and sometimes the 4-person cabins sell out. Some rooms have pull-down bunks, while others have a pull-out sofa. If you're concerned about bathrooms, google the ship's deck plans and choose a location near a public restroom. Or -- better yet -- choose a stateroom near the gym; when it's time to shower for dinner, someone can go to the gym to shower (the showers are nicer and larger than the stateroom showers). 4 in a room IS tight, but it's do-able if you don't over-pack and if everyone has a good attitude about it.
Occasionally it's cheaper to book two connecting inside rooms rather than one larger room for 4, and that gives you two bathrooms.
Everyone says Carnival is cheaper, but I guess I'm just missing their really good prices. I only compared their newest, largest ship (The Dream), and the prices were within about $100 of the other large lines. I don't want to save money by going an older ship that doesn't offer all the amenities.
If you don't care about your room so much, consider booking a guarantee. Let's say you book an OceanView Guarantee: you don't get to pick your
specific room, and you're promised that you'll receive AT LEAST an OceanView room. You could be bumped up to a balcony or even a suite. You're not likely to get a prime room this way (i.e., if you're lucky enough to get a balcony, it'll be in a less-desirable location), but you will spend less on your OceanView, and you
could end up with something nicer. I've done it, and I've always been pleased.
Is there a port to which you can drive? If so, look only at ships sailing out of that port, and you'll save airfare. I tried and tried to figure out a way to fly to Miami next July, but with six peope . . . it's just not going to happen. All six of us can drive down for about the cost of two people flying.
Whether you drive or fly, plan to arrive a day ahead of your cruise's departure. Too many things can happen to delay your travels, and IF you're late . . . the ship will leave without you. One night's hotel is cheap insurance. Many hotels in port cities offer good deals that allow you to take a shuttle to the cruise terminal /leave your car parked in their lot. Parking at the port = $12-20/day, depending upon your port, so that's significant.
The time of year matters a great deal -- I'm talking Caribbean here; I don't know about Alaska and other parts of the world. Summer and holidays are always going to be expensive. Fall is very affordable, though it's hurricane season; if there's a hurricane, the captain may take you on an entirely different route than you'd planned to go, but you won't be in any danger. It IS possible, however, that you'd have trouble getting to/from your Florida port city because of the weather. January/February are the least expensive, and the weather will be okay down in the Caribbean, but it'll be (relatively) cold in Florida and on your first day out/last day back as you come/go from Florida.
Many people assume that once they've paid their cruise ticket, they're done. They think it's all-inclusive, but that's not true. You MUST budget for your tips, which run about $10-13/day/person. This is for your room to be cleaned every day and your meals to be served 3xs per day, so it's a very fair price. Also, most people spend heavily on drinks: On most lines you'll get tea, lemonaide, fruit punch, and coffee free anytime of day. Milk and juice are free at breakfast (you can bring them back to your room and store them in your room cooler -- like a 'fridge, but not so cold). The soda package is a rip-off; it's better to buy a few sodas individually -- or, better yet, bring them onboard with you. Alcohol, of course, is very expensive; that's where they make most of their money. Entertainment is also included in the cruise price; expect a live show every evening and other things throughout the day. Kids' activities are included in the price. They'll have a couple specialty restaurants for adults only, which include an upcharge. Since you're looking to cruise on a budget, you should investigate these options and decide what you'd likely spend; many people spend as much on "extras" as they do on the cruise.
Budget for cruise insurance. The cruise line offers it, but it'll be cheaper through other sources. IF you should become sick onboard, it's very expensive to be treated by the doctor onboard, and your medical insurance may or may not be good (you should check on that). Also, it's very unlikely, but IF you were to be injured and need to be airlifted back to an American hospital, cruise insurance would pay for it (airlifting would cost about what I bring home in 6-8 months). Be sure of what you're getting; the common things are trip cancellation, medical, and rescue airlift.
Bring with you everything you need: Bandaids, asprin, sunscreen, disposable cameras, seasick meds -- you get the idea -- these things cost a fortune onboard, and the ship's stores aren't always open.
Be sure you have the necessary identification. Check on the cruise you're considering and see whether you can use a certified birth certificate /driver's license, or whether you need a passport. You can't get these documents at the last minute, and some of them are pricey. IF you need to buy passports for your family of four, that's going to run about $400 -- which is enough that you'd probably need to budget for it too.
When your ship stops at the islands, you can save huge amounts of money by NOT booking the ship's excursions. They use a scare technique to get you to buy: They say that if you're on their excursion and it's late, they'll hold the ship; if you're on your own, you may be left behind. You can read a wristwatch, can't you? You're not dumb enough to get stinking drunk and be unable to find your way back to the ship, are you? Then you'll be fine. Just don't cut it too close. You can find wonderful things to do via internet, or you can just visit the shops and the beaches near the port. You can spend as much or as little as you like in port and still have a great time. I've had wonderful times in ports doing expensive things (dolphin swim, ATV rides), and I"ve had wonderful times just sitting on the beach.