Update, this thread has been such a help, hearing all the opinions. I accept that by taking possession, or sending someone to do so on my behalf, I am basically accepting the goods as they are. Having said that, it isn’t obvious at a glance that it is a different model, and takes a bit of digging to find the spec. As others have said, he couldn’t be expected to cover transport to Timbuctoo as he’s selling it from his door. So having had such useful opinions on the matter I was able to take a reasonable stance with him, and we’ve come to an arrangement. He’s going to send me £250 which can be justified as either the difference in value between models, or the transport costs. I will sell the stove and see what I get. He’s even offered to look at sharing any loss I make too, and I will do the same if I happen to sell at a profit, however unlikely that may be.
And I’ve also learned that there are much cheaper options around than I used, just hadn’t properly looked into couriers or pallet services before, so thanks for those suggestions too.