I had a 1.42ghz Mac Mini G4 before that I bought off of Craigslist back in March 2006. I put Leopard on it in Fall 2007 and it got pretty annoying after that, even maxed out to 1gb of RAM. It died recently in our house fire so I'm about to replace it because I like having a simple computer on the main level for simple tasks and sharing our all in one.
When I bought my 1.42ghz Mac Mini G4, I bought it for $375 and it HAD JUST retailed for $599 a few months prior. The person selling it just wanted to dump it, and I made my low offer based on the update which occured to the mac mini line right around Jan/feb 2006.
I'm trying to pay as close to $400 for a used Mac Mini Core 2 Duo that's still within warranty. There's nothing on craigslist near me; however, there is a candidate on ebay. Let's see if that works out. on ebay, I would ultimately end up paying more and would really prefer craigslist.
btw OP, you should make this subject more meaningful than just "this mac mini"