Should I do anything about this cat?

The taming of feral cat's tends to take a number of months depending on the cat and their experience with people. I personally would recommend finding someone in your area that has dealt with feral's before as they generally are very aggressive. They also can be quite dangerous to deal with. Also I do not recommend selling the cat as it could be a liability for the store. If there is a feral colony in the area you will want to get with the local shelters in the area to locate a care taker for the colony. They will do a capture, spade/neuter, and release of the cats. This will insure that the colony will not get any bigger and at the same time keep other feral colonies from moving in by keeping the original colony in place. The care taker will also see the the cat's needs for as long as the colony is there.