I've just been in the same boat and decided last week to just go for it and buy the PSP-2000 (slim), although the new PSP-3000 has a much better LCD screen and also a built in Mic for Skype etc. So really its down to whether you care about the better quality LCD screen or not.
Also it is rumoured that the PSP-3000 can't be modded (for the moment atleast), that was the deciding factor for me so I went for the current PSP Slim because I wanted to run homebrew and rip all my old PS1 games to play on my PSP, so I sacrificed the better screen for the ability to run my UMD/PS1 games from the Memory stick.