I've done this personally in my own name. Can't see why you couldn't do it in the PTA/PTO's name with checks written payable to the PTA/PTO. I would make one person be the contact and take items in for sale. You really have to get familiar with the shop's standards - they typically are high and things should look as new, current style, etc. Also most shops limit the number of items you bring in at one time since they have to check it all in. These are typically independently owned shops so their policies will vary.
My experience with donated items was when we asked for as new stuff for the nurse's clothes closest we got many, many items that were hardly fit for the thrift store. My personal experience with consigning was very positive.
