Selling items with your pet is a very handy feature, but does it net me as much money as I would've gotten had I used a town portal scroll and sold it myself?
I met my first underground merchant, which makes it easy to address this question with science. This is what I had in my pet's inventory.
The salesman offered a total of 1,039 gold for these items. And well, ...
It appears there is no penalty for selling items through your pet.