How can a 12 year old make money quick?

I'm 12 and I really really really want the HTC Flyer. I saw it on ebay for a bid..it was 20 dollars even though it's really worth about 500 dollars. I don't think I should attempt to buy it, because it may not be the real thing, Anyway, how can I make money to get enough to buy a new one from the store?? Thanks in advanced.!