should i buy PSP

I really recommend PSP. It was my first portable console and gave me a lot of fun. But remember - if you want to play multiplayer you won't be able using PSP E-1004 Street. The newest with WIFI is 3004. But it's not produced anymore.

maybe you should think about buying a used one from ebay. bought one this year for 30€

I love my psp to death, and it was my constant companion until i got my galaxy s3. Psp has emulators for pretty much everything before the ps2 era.
But nowadays I'd recommend a good Android phone and use that for emulation instead, with some kind of gamepad. Hell, there is even a psp emulator on the google play store, which actually Kinda works! Not to mention the DS emulator.
Get a good Android phone and you 'll be set for years :)