Believe it or not I used this service last week and it worked!
I bought a broken PS3 off of here with the intent to fix it with a new HD, this didn't work so I was left with an expensive paper weight and a nagging wife who was questioning my sanity for wasting money on a knackered gadget.
If I broke the warranty seal to open the machine I was past the point of no return and I could have spent lots of cash on bits that didn't sort the RLOD.
Then in the search for bits I found said auction, the one I bought was £25 and I thought hell its worth a go, if its a scam then paypal will refund me. The guy emailed asking for the serial number and my address (was thursday or friday). I never heard anymore on friday/weekend/monday and thought the worst. Got a call from my wife on monday afternoon saying there was a courier there with a box. To cut a long story short it was a replacement 80GB PS3 with protective plastic over the sides (mine was an 20 month old 40GB), courier swapped it, put my broken one in the box and off he went. So far it is working perfect and have had no dodgy follow ups so far.
To be honest I was stunned that it worked, don't ask me how, the only dodgy thing was that it wasn't my name on the package but the right address, I assume it was the person involved with the auction.
All in £85 broken PS3 + £25 auction = £110 new 80GB PS3

Just the wife to convince now, told her I was going to sell it for a profit..........but I'm not.