One way to cut down on costs is to bring breakfast foods for the room. Things like granola bars and cereal bars travel well. Even some of those individual cereal things that you can pour milk right into. You can get them at home much cheaper than at Disney and then you can just get milk in the food court. Think about bringing some snack foods too to take into the parks, just be mindful that in the summer, things you don't expect to melt will.
Do look into the offsite hotels that have a shuttle. They usually charge for it, but if you can find a good enough deal, it might be worth it (and it pains me to say that because I'm very into staying only onsite...but with 5 people...). Hilton Garden Inn Sea World has a Disney shuttle, as does the Hilton Grand Vacation Club Sea World. Sheraton Vistana does too, and you can usually get a pretty good deal there, and they have bigger condo units.
For tickets, certainly check undercovertourist, but if anyone is a
AAA member check their prices too. My AAA office has always had either better prices than
UT, or prices within a dollar. To not have to risk tickets getting lost in the mail I will happily pay one extra dollar (since I'm still saving money over buying through Disney). You'll need to actually go into the AAA office and ask for their price list for Disney.
For table service meals, I like to go at one of their last breakfast seatings (10:30 or so). Then it's more like brunch and I don't need to eat more than a snack again until dinner. This may or may not be an effective strategy for the guys in the group, but snacks are cheaper than full meals. By doing a late breakfast, you can experience the restaurant and the breakfast menu is MUCH cheaper than the dinner menu. Captain's Grill is one of my favorite budget TS breakfast places. They have both a menu and a buffet. Menu breakfast items are $10 or $11. The buffet is about $18 per person (CHEAP for a Disney buffet) and has a very large variety of food. When I do the late breakfast thing I either do it on a non-park day or on a day where I've gone to AM EMH at a nearby park (EMH at MK, then breakfast at Kona for example), and so I leave the park as the crowds are getting bad and then go back after a refreshing breakfast.
If anyone in your family is a BJ's member, they sell discounted Disney gift cards. It's not a huge discount, but buying a $100 gift card for $95 is a help, particularly if you're putting it towards something expensive like a room. I do buy them for expenses too though. Or if anyone has a Target red card, the 5% discount works on Disney gift cards when you buy them at Target. Again, a little savings, but it does add up.