Personally no. The guy has shown his hand, he'll be bidding 17500 at least. I reckon Kev's probably nearer the mark.
I sold a digger a few years back, I bought it for 3k after messaging the eBay seller with a cheeky offer. A year later I put it back on eBay auction and got offered 4.5k to end early which I considered TBF. Ended up at 7.5k, god knows why but the winner turned up, paid cash and left me great feedback. Go figure.