I could be wrong, but I believe that you can do a BTO from the Apple retail location. Depending on what you want, and what they have in stock, you might be able to walk away with it the same day. I will probably go there when I get my next Mac. More so because there is one about an hour away from where I currently live (was 10 minutes before, but I left that place before they opened). There is no sales tax there, and I wouldn't have to pay tax by taking it between states (would be impossible to enforce anyway). Most places that I have called that ship items would let me get away without the tax (the ones that claim that they must) if I had it shipped to someone I know in NH (I live in MA). I might do that next time I have a large purchase, it's not worth the effort on small items.
There are phone numbers listed for all the Apple retail locations, just call the one near you and see what they can do for you. You could be happily surprised by what they tell you.