Please check out this thread:
It is not true that Target stores sell them every Sunday. They usually sell them as they get them, although many stores are currently holding them for a big sale on the 21st. You should call your Target and see if this is the case. Best Buy is probably going to have a sale on the same date. TRU and CC are selling them as they get them, as far as I know. You should get yourself set up with itrackr to find out about your area specifically.