Having a real CB shop is about just four things - IMO. First two, knowing enough about the way RF behaves and about RF electronics. Then - and this is the tough part - having a great deal of experience with a lot of different radios. Knowing intimately many radio brands and their problem areas with constant exposure with them. Lastly, it takes an honest guy willing to work for relatively little money and maintaining excellent customer relations. Sounds a lot easier than it is in reality. Many variables; with little reward and constantly seeking new customers.
You could make more money as a construction contractor and own all of the radios you want from earning a decent living. You could still play with radios as a hobby and learn that way too. CB radio isn't exactly a booming industry. But if you go as far as to learn RF electronics, you could do repairs on Ham radios. There is some money in that. Not much; but some. Used to have an automatic transmission shop, because everybody has a car and they all need to be fixed at some time. There was money to made with that. Playing/aligning radios now as I'm semi-retired . . .