Hi efript.
I understand you, but maybe there is a 3th way. First, buy the components at some reliable on-line store. Don't worry about config or store. Here you can ask about and people will help you a lot, and also will learn about what is going on on the computer world.
Second, if I am not wrong, there are some places where tech's build for a reasonable fee your computer. They know what they do, and you can learn the way to do it, so another day can do it by yourself. And also, I'm sure you will save some money.
Good luck!
DIY: read, buy, test, learn, reward yourself!