Fr8,
In Mempho, I went to the Apple store at Popular and Germantown (Saddle Creek?) and spoke with one of the managers. I think all you need to do is show up with your ID and checkbook or plastic. I cannot remember if it's 6% as mentioned above or 8%. Of course, if you get it in MEM you'll pay 8% sales tax so you're essentially getting it tax free. You may be able to order it from that store and have it shipped to your address out of the state and save on the sales tax. Just call them and ask them.
I have never tried to use the FedEx discount outside of MEM. Let me know what kind of success you have.
BTW, PC Mall/MacMall has a distribution center on Shelby south of the arpt. You can get stuff there at a discount or brand new stuff off of the shelves. The discounted stuff is mostly returns and some minor repairs and/or missing components. For example, I bought a printer there that was returned because it was missing the CD that had the printer drivers on it. I just took it home and downloaded the printer drivers from HP's website.