sounds like you don't really know what you want. buy something cheap to start and upgrade when you have an idea of what you actually want to upgrade (and have an idea of what you're actually willing to pay for certain upgrades).

also, even with a cheap bikes direct bike, all of the fittings, threadings, etc are standards, so you have limitless possibilities of what you can upgrade, and you won't feel limited at all. by the time you want to advance from a standard 4130/reynolds 520 frame, you'll definitely have a proper idea of what you're looking for, as well as the idea that 4130/reynolds 520 is a good choice for an around town bike, anyway.