In the UK we have Gamestation stores and they stock a good selection of retro stuff in which the PS-One new and old shape model are readly availabe. Expect to pay around £20-£35 for a second hand one with 30 days warrenty.

It would be wise to buy later models like the 75XX series as they are more stable CD lens & internal build than the 5XXX series and the original 1XXX series. The remodel white PS-One is a good buy.