Hi tinkie,
I haven't read every response but have read a few so sorry if I covering something someone already covered. I am working my way up to yearly trips and have taken everytype of trip to date both onsite and offsite. Onsite will almost always cost you 1/3 to 1/2 more than you will have paid staying offsite. Not to mention that staying onsite generally will always cost you more food wise than offsite.
If you want to do more trips per year then your best bet is to by an AP and stay offsite. There are plenty of people who never stay offsite on these boards and would deter you from doing so. I have done both and will admit that it is great to have a trip onsite but you will pay more to do it and honestly, I have not had one bad trip staying offsite yet. If it is your intent to go more than once a year then offsite is your best option.
I say buy an AP as it pays itself off at around the 8 day mark. Point is to go as many times in a year as you can. As for offsite, Priceline (look at a site called biddingfortravel.com before bidding on priceline), Skyauction and HotelKingdom are ways to look into making a trip extend itself without being overly expensive. Now, honestly, plenty of people will tell you to wait and get AP discounts and stay at the AS or Pop Century. These are really nice Disney hotels but you are staying in one small room and a week even with the discount will cost you $400 plus. You can rent a 2 bedroom condo from Skyauction from $300-$400 for the same week. You will then have a full kitchen, washer/dryer, living room/dining room area and two bedrooms. Not to mention that it is easier to fix your own full breakfast in the a.m., bring sandwiches in for lunch and snacks and then are only left with having to purchase dinner in or outside of the parks. This also saves you on packing as you will only have to pack for 3 days and wash clothes every 3rd day. Staying in one room at the AS/PC allows you to do these things but everyone is crammed into one room, your limited as to what you can eat for breakfast in the room (or having to refill icechest on a daily basis) and you will have to pay to clean your clothes in the laundry room. However, you will have Disney theming and Disney transportation. P.S. Having an AP means that whether your staying on grounds or off grounds, parking is FREE.
I have yet to experience an offsite stay that has taken me longer than 15/20 minutes to reach Disney property and I never sit in traffic on I-4 unless I am visiting US.
My current way of saving for my next trip is I am bringing in my lunch to work and saving the usual $5 I would've spent plus whatever change I have saved at the end of the week. Most weeks to date I have managed to save $20. So as I will be saving almost a year by the time I go, I will have saved about $900. This will certainly pay for my room and ticket, then it is only food and souvenir money that I have to come up with.
Look into all your options and create a budget. You may be surprised at what you'll discover.