Needs for starting a small business

I've been contemplating looking into starting a local small business dealing with designing and creating custom computers(pretty much what we do here)

I have run into some theoretical obstacles:

I obviously need more than just my hobby as experience and require substantial training and certification. What type of certification would I need?

I would not only build the computers but would need to facilitate labor/warranty for X amount of time after purchase. That requires training/certification for OS as well as a basic understanding of simple electrical engineering principles.

Or conversely keep a substantial stock of all parts and just act as a hub for RMA turn around and provide quick replacement parts for the customer while I deal with the manufacturers warranty through my own stock.

I don't believe I have a customer base. Here's the way I see the Prebuilt computer market:

Cookie-cutter office/home PC: Dell, HP, Compaq etc make these types of computers. Low budget, low power, low-usage demand by the end-user. The type of computer your dad/grandpa/schools use. This would not be my competition, because I would use quality components that would place me in a higher price bracket, and the uninformed couldn't distinguish between the quality of components.

Custom Gaming/Enthusiast/Overall Custom: iBuypower,CyberpowerPC etc. These are made for more advance users that have a basic grasp of need vs. specification. This would be my target customer base, but once again I run into a dilemma. Usually users that want a high end computer, but lack the ability or confidence to build one shop at these sites. The computers I would build would be made from high end components and once again would be a higher cost.

My target customer: Would be someone knowledgeable enough to recognize high quality components. The problem is, generally if someone is knowledgeable enough to identify quality components, they are perfectly capable of ordering and assembling the components themselves.

So in essence, I lack a customer base to build computers for.

Obviously this is only in a brainstorming phase, but this hobby is something I genuinely enjoy doing. I've been in the military nearly 13 years, and as my retirement get's closer and closer, I have to contemplate my next job afterwards. The military provides tuition assistance as well as up to 4,500 towards a technical certification(1 time) so I believe now is the time to look at what type of education I need as a foundation for a business venture.

Pending what's talked about here, my next step is to talk to local independent computer stores and ask them about their experience with customers, supply/demand.

Any advice, insight or general information from this community would be appreciated as I kind of piece this together in my head.