In many cities in the US, there's Microcenter, where you can walk out with every part you need. We also still have smaller stores that can build clones for you/hand you the boxes, but they don't quite have the same variety of parts.
Microcenter is one of the very few local DIY stores remaining. Best Buy has some stuff like hard drives but, even in the Boston area, I can't think of many other examples at this point.
Of course, you have Newegg and other online stores.
In some cities.
I happen to be from one of them.
Now I live in a far bigger city (Los Angeles) and the closest Microcenter is 2 hours away. Worse with traffic on a Tuesday afternoon. They’re only in a handful of states, sadly.
There are not many places that offer a reasonable selection of boards that are close. Fry’s was the last bastion for many folks. Best Buy sometimes has a few options. But today is a far cry from the days of Circuit City, Computer City, CompUSA, RadioShack… not to mention dozens of mom & pop stores. Online is the main way nowadays.
