So, Lex, I've been thinking about your fundraising idea. Assuming it's something you really want to go through with, you're going to be giving up some cool shit you may never get back. Of course, there's the possibility you'll he doing so to fund an experience you may never get to have again, so you weigh that.
Anyway, if you do go through with it, the way you're going to want donations to work is like so: Rather than first come-first serve rewards for big donations, you're going to want to do drawings where your donation level makes you eligible for different prizes. You figure out what those should be (maybe it's 1/4 of the item's value or something like that).
You can still do the used games incentives for the 20/30 donations, but this way, instead of getting one person chipping in for one item at a big price, you get maybe ten people chipping in for the same item at a lower price that adds up to more than the one big donation would have been.
Of course, that makes advertising this in the right places all the more important, so plan carefully.