My mom's response to "I'm booooored..." eventually became "I can give you something to do!" (e.g. washing dishes, vacuuming, math problems to solve, books to read in Russian, etc). Guess how long it took us to stop asking! ;) When you're feeling less snarky, you could just make productive suggestions. "Did you finish your library book(s)? We could get you new library books." "Did you finish your craft project for Grandma?" I don't have kids but I have sisters 5 and 8 years younger than me, so I remember them and their friends as kids pretty well. And I think all of us went through phases of "boredom," probably around the time we learned about computer games...but we were also kids and not mature enough to independently come up with alternative ways to entertain ourselves. We had tunnel vision.
Do you get your son random things he asks for? I don't remember my sisters or me ever asking for or getting toys/stuff in elementary school, except for birthdays and Christmas, when we were asked what we wanted (but didn't necessarily get everything we asked for). I think we knew it wouldn't be forthcoming until then, anyway. We did sometimes ask for sweets at the grocery store...because that *did* sometimes work. (We didn't care about things like clothes yet.)
Disneyworld is hard...it's hard to be left out of something that *seems* so important, that your whole peer group and especially closest friends are doing. Theme parks are kind of dumb, but 6 year olds don't know that. And they idealize things, and build them up, oh so much. If I wasn't in debt, I would try to make it happen. Although I think I would sit down with the kid and teach a hard lesson about tradeoffs. Like, we can go to Disney in a year if we give up ice cream and going to movies and you chip in half your allowance. Even if those things don't make a huge dent in the budget. Maybe I'm a softie. Or maybe I remember feeling like I was missing important experiences (an 8th grade science trip and music classes) and being really grateful that I got to experience those after all. Also the only way I found out theme parks were pretty dumb was by actually going a few times (not a regular thing for us, the camping trips vastly outweighed Disneyland and Legoland and all the other lands and worlds). I don't vouch for this being the right answer or anything; I just don't think I could keep blankly saying 'no way' if there was.