Don't do the eBay. It's sold out only because of Sony's inability to produce mass quantity to meet the release date, not because it's in demand. PSP was outsold by GBAsp in its first week of launch and none of the killer titles have sold as third as they were expected to sell, extreme case being Puzzle Bubble only selling 540 units on its release date. In short, PSP is the next Dream Cast.
It's also known to have been cursed with first lot defects, such as the machine not turning on, UMD slot popping out, tons of dead pixels, etc. And Sony's customer service has been really bad in dealing with these problems, many of which they only acknowledge as "features" a la Microsoft. Many people are quite upset at this and gave PSP a glorious nickname "gokiburi," cockroach.
You can go search for the source of my information, but I'm not going to bother posting references in Japanese here.
PS. I'm not a Nintendo fanboy. I just wanted to save you some troubles, that's all. If you must get one, wait for the US release so that all the hardware problems are solved.