Is there away to adjust the sell price for cards once they have already been listed? I did the mass pricing.

Thank You.

To individually set pricing:
Click on your tradelist and cards for sale and click on the price in the yellow collumn labelled "$".
OR
Hover over a row and click on "Edit"

To batch price once again:
Do as you did before (Tools > Price All) and it will overwrite with the new auto-priced values as you designate.