Totally different out here in the midwest. I have never heard of anyone driving across state lines (around here) to avoid paying sales tax or of a store that would omit the tax just because the person said they were from out of town.
Actually, the state of Delaware does not have a sales tax for
anyone. No one asks if you're from out of town. They just don't have a sales tax, period. Delaware is very pro-business and has banking-friendly policies (this is why many credit card companies base their operations there... though if you look at it the other way, Delaware has a LOT to do with why credit card companies can get away with so much) and the so the corporate income taxes they receive tends to offset the need to charge a sales tax.
And in the northeast, states tend to be smaller than in the rest of the country. From the NJ/PA/MD/DC area, it's a 1-4 hour round trip depending on where you are, and in a car with good mileage it's about $25-$35 in gas at current gas prices. When you're buying a macbook pro, that means you're easily saving over $100 if you're willing to invest the time. Plus you get instant gratification, and if you qualify for an educator or employee discount of some kind, those stay intact as well, saving you even more money.
To the OP: Unfortunately pre-configured CTO systems aren't commonplace at the Apple stores, because by definition, they're custom orders and aren't likely to appeal to enough people that they'd be guaranteed to move that inventory. They sometimes stock one or two models that are the most common CTOs, but everything else they would expect you to buy online.
Apple isn't taking into account that people are traveling far and wide to save on sales tax. Or, they're probably assuming that if you're willing to do that, then you're likely going to settle for a "stock" MBP.