apologies for posting months late, but I still love my psp. I have one from when they first came out (the 1000, from 2005, although the umd drive has died, but it still downloads and plays wireless against my other one) and a slim (the 2000, from 2007) which is still going strong. In fact I travelled with one for a year once and used it to do my banking via the very, very basic web-browser; stored my photos to show people; listened to music etc.
I'm probably going to buy a 3000 from the US as well so I can make sure I can still play all my games in 5 or 10 years, although I won't buy the E1000, sold in Aus/Europe, which doesn't have wireless. second-hand 2000's or 3000's should be $70-$90, although you'd be able to pick one up on ebay with a bundle of games for $100-$150.
loads of games available for $15 now in the shops, some absolute rippers. And it is the business for old arcade classics, retro games etc (check out - The Sony PSP Retro Compilation Library | RetroGaming with Racketboy
I must have clocked up thousands of hours on mine, especially puzzle games - loved lumines and lumines II to death, every extra extend, gunpey. loved tekken, sf2/3, blazblue. loved williams/gottlieb pinball (arcade perfect recreations of tables from the past 50 years).
games aren't region-coded, so you can buy them from anywhere.
the new PS Vita looks cool, but is EXPENSIVE, and there is no backwards compatibility with umd discs (which has put me off buying one for the moment). the psp is also much more of a serious gaming machine than the DS/3DS (of which I have both - the 3DS is fun, though, especially for my young kids).