How can I start a retail repair station?

Well, I hate to state the obvious, but in most cases, it's no more complex than you think.

You will need to find the site, get your permits, then start getting customers.  Remember that acquiring things like the permits are the easiest part--it's the attracting of customers that will take the most work.

As for doing it more as an investment, take a look through brokers and websites to see if there are any already running in your area for sale. You may be able to buy it and hire a team of people to run it for you from day 1.