Ebay maybe. It's blocked at work, so I can't check for you.
Keep an eye on Craigslist. The CFW box in my sig was acquired on Craigslist for $50 with a broken laser. It was on 3.01 and hadn't had a game file saved to to since 09(bought this year). Check other sections than Video Games or electronics. You just have to find someone who doesn't know what they have.
i have seen a few on ebay. But most of them arn't cheap here is one You must login or register to view this content., but not sure if its on 3.55. You have to check.