Seems to be quite a lot of negative responses here. I say that you can do it - it just won't be easy. Disney is expensive, no doubt about it but don't let that put you off. There are nearly always people willing to pay for you to do chores like washing cars, cleaning / mowing gardens, babysitting etc. You will have to work mega hard but if you really want to go to Disney then its worth it!
I don't think the messages are necessarily negative, just realistic. Sure, a 13 year old can raise money for a trip to WDW, but it won't be easy.
My 2 cents? Instead of trying to raise the money necessary for the whole trip, start by doing whatever jobs you can do to raise money for the park admission you want. You can buy those in your local Disney store (if you have one), your local AAA (if your parents are members) or online (with a parents' credit card). As long as you don't lose that park admission, it's good until you actually use it. This way, even if the rest of the friends flake, and it takes you 5 years or more before you can get to WDW yourself, your park tickets are covered (and at today's prices, not the adjusted-for-inflation prices in the future). Once you have your tickets covered, and you know your friends have purchased THEIR tickets (no sense planning further until you know you're all responsible enough to at least get that far), then you can start working towards saving $$$ for the room(s). Not know where you live or how you'll get there, you may also need to save air fare.
I wouldn't say your goal is crazy, but we've no way of knowing anything about you and your friends, how responsible you are, what kind of money you can be expected to make in your neck of the woods doing jobs 13 year-olds can get. When I was 14-15, a sophomore in high school, I got an under-the-table job washing dishes to pay for a band trip to Quebec, and a Spanish class trip to Spain. My mom helped with what she could, and most of my birthday & Xmas presents that year was cash to help pay for the trips, but at least 75% of the money was based on my hands getting all pruney and being chased home by feral cats because I smelled like seafood. That was when minimum wage was $3.35 an hour, and I was getting 3 bucks an hour (but no taxes! Yippee for me!) because you really weren't supposed to work in a kitchen unless you were at least 16. My senior year, I was working in a fast food joint and paid my own way for my senior trip to WDW. Granted, even getting paid under the table will probably get you more money than I got then, but it's not like WDW is CHEAPER than it was when I was a kid. Only you know (or will know) if you can find the kind of work necessary to raise the cash, AND if you have the discipline necessary to NOT pay for immediate things, clothes or video games, etc. And of course, some parents feel, if their kids are earning money, they should contribute to the household. Even if YOUR parents aren't like that, the parents of your friends might be, which will make saving money harder for them.
Better yet, whoever the ringleader is on this plan should try to get all the kids and their parents together to discuss it happening. First of all, you might discover some of the parents have no intention of letting their kids go away without them. On the flip side, you might find some parents who's really want to go and be of greater assistance. They might know people looking for kids to help in their stores, or mow lawns or babysit. And they might be able to help you budget the money necessary to make the trip happen. A lot of guesswork could be removed if your friends and their families get together to discuss it. And if you're lucky, someone will order pizza.
Good luck, and just remember to be realistic about the goal. Some of your friends might not have the means to make the money, or the discipline to NOT spend it. It doesn't mean they don't want to go, it means they're teenagers.
Don't always have your head in the clouds, and always keep your feet planted firmly on the ground.
