Well, that is surely open for debate… If he’s just a traveling merchant, then yes, probably he’d prefer some variety in what he sells. But considering that he a) so far only sells stone things and b) is actually called “Someone’s mason cart”, I believe he’s a specialized vendor, so why wouldn’t he buy more stoney things, to keep his focus on stone wares, and sell them on to the next village he visits? ^^
This might get a little out of hand now, but it would be awesome to have even some bit of “economic simulation” in the background. The player always keeps buying all the wood? The prices should slowly increase. The player always sells of tons of stone tables and garden gnomes (that’s what I tend to do ^^)? Those prices should drop until merchants don’t even take them anymore. This would obviously strongly encourage trade-oriented gameplays to keep a stock of a variety of things, to be able to sell the most profitable things at any given time.
And since we’re already getting a little crazy here, let’s step even further into the realm of unnecessary overkill, and synchronize this behavior (through Steam or the SH servers directly) with all other players to maintain a global “Hearthdex”!