Could he have been stocking them for a few months?
My friend gets roughly 70-100 stacks of herbs a day in he makes to glyphs,
Personally if I made DMF decks, I'd rather save them and sell in bulk and get a load of gold in, and lose some of their value with time, than sell one or two at a time when their most wanted, cause I'd spend it straight away
No...as in over the last month and then put them up when Darkmoon Fair is active, since that is pretty much the only time they are useful....
Yeah, no. You DON'T put them up when it's active, as that is the time most people turn their Deck's in. You suggest that this guy is a clever Goblin, but he's actually quite the opposite. Furthermore, this amount of Trinkets is way too much to be realistically selling in one week. The hastiness and willingness to dump his own prices every few hours should tell you enough about his "business-model".