Just looking to pick up a PSP for a good price now but with there being so many different models i'm getting confused
Well they were released in this order
The black sheeps are the PSPGO! (no UMD drive, download only) and the E1000 (final cost reduced model, mono sound without headphones, other features cut out).
The original 1000 series is more sturdily built but has a shonky d-pad for 2D fighters. These are the oldest models so are probably the most likely to be damaged/knackered in some way.
the 'slim' 2000 series models are often cited as the best due to a much better screen, more lightweight design etc.
The 3000 looks the same as the 2000 but has a few additions such as a built in mic and something to do with the wifi (which I never use). I have this model and really like it but the 2000's screen is apparently slightly better from what I have read.