To all the mediators out there who use stones to meditate, is it OK to use a stone that was bought..

It depends. By clothing store are you referring to a new store, by that I mean a department or fully clothing store, or you referring to a thrift/clothing store like Goodwill or Salvation Army. If you are referring to an actual clothes department store it would not be a problem. It is the person themselves that makes the meditation stone what it is. They would do the blessing rite. Now I would say that if it was a thrift/clothing store then no I would not use it. Meditation stones or any kind of religous/mystical device can be harborers of bad things. If you got it at a thrift store, you would have no idea what kind of person had it before. The kind of things he or her did or life they led. It could harbor demons or be curse. So if it is from a thrift store than no do not use it.