I would just call your local store. They may have a good idea by now.
Just got off the phone with my local Radio Shack. Clerk told me that they actually have extra 4S's, but their "district manager was going to be taking them". He told me that I could just preorder and I could get one no problem. I then asked if I would be able to get one by tomorrow, and he said I could only get the 16gb tomorrow, then retracted that and said I would have to wait until next week... I then asked about the mysterious 4S district manager situation, and he said "I'm not sure what he's going to do with them, seems like he's trying to make it so they only way to get a 4S is to preorder."
Huh?? I then said I'd be willing to preorder NOW for one of the extra's that they have, but he said I'd have to wait until next week...