I don't own a PSP, but here's how to value yours:
Rough loose ranges (USD): 1000: $50–$90; 2000/3000: $60–$110; Go: $80–$140; Street: $40–$70. Bundles + games add value.
Sell on eBay, Mercari, Facebook Marketplace, or retro shops. Clean, photograph well, disclose flaws.