How much were PSPs when they came out?

Excuse me, I was wondering if you could possibly shed some light on a historical matter for me. Specifically, I'm curious about the initial pricing of PSPs, or Portable Sony PlayStations, when they first hit the market. Do you have any idea what the going rate was for one of those devices back in the day? I'm trying to get a sense of how much they've appreciated in value over time. Any information you could provide would be greatly appreciated.