Call and ask. Pretty sure they do. Bought from them many times, but never tried to sell them anything.
Don't know just went in outbof curiosity
I don't think so, but there are other stores that grade and buy they comics.
There is a part where they sell comics which is pretty obvious are pre-owned but I wouldn't know what to answer... I don't know if they take single issues or just hardcovers or under what conditions
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