I accidentally bought the wrong shirt for my avatar in a shop, is there anyway I can sell it back to the store to get at least some money back?

The Sellback Store of course. You can sell your items back for 50% original store price.

there is a sellback store.

It is not on the map, but click the link above the map, and scroll down, and you will see the shops name.

Haha, thank you guys very much =D

Is there a way to get to it without clicking that link? (For future visits)

no, that's the only way to access the store listing.

you could always bookmark the individual store's URL if you wanted to though.

Yeah, the Sellback isn't on the map (why is that, anyhoo?) so you'll just have to use the link in the list.
Bookmark the page if the link is too troublesome.
^^

It was added AFTER the map was added. So it hasn't been added yet. And I'm not too sure if it will; as I only recall there being one open spot on the map. Or maybe I was wrong. I haven't looked at the map in a long while. I just use the shop list. Anyways, if you take notice, there is one other shop that isn't on the map. Quercus Magus -- it holds the Faerie Wings, True Love and Pure Hatred Wings and the love and Bitter Hag as well as the Luuuv Guru.

I doubt that the sellback store will get a place on the map, as it has no merchandise to display.