Starting off as a Custom system builder

I want to start building custom pc's for people, but seeing how no one in my family needs one and everyone at my high school is a console vegetable, I would have to find clients over the internet. I was wondering how I can get my name out there so people can trust me to handle their hardware and such. 

Well its a really niche market as most people who would seek out someone to build them a custom pc could probably build one themselves and would rather do it that way since its cheaper and is relatively easy, unless you're really good at case modding and doing custom water loops (something outside of the realm of your average builder).  Your best bet is being that guy who can trouble shoot people's pc's and being known for that until eventually someone might ask you to build a computer.  The desktop market is getting smaller as a lot of people have shifted to smaller form factors because for what most people do they don't need a desktop pc especially a custom one.

^ yea. Unless you have some crazy unique selling point, its not really a viable career move. Heck if it were I'd be doing it too.