Wow! Why so grumpy, Jim?
That... wasn't grumpy!
Seriously, it's a shame how many folks get into the slot car retail business because they think it's easy. Those folks fail. They fail partially because of the factors that set me off on that rant. Just saw this very thing this last Friday in one of our fine NorCal emporiums. To succeed in this type of a business, you have to nurture the beginner customer rather than take their money and not do the follow up.
BTW... none of that rant was directed at our OP here. He hasn't gotten started yet. He has an opportunity to start up slowly, keeping it simple, and to make sure his customers are properly informed. Kudos to him for doing at least some basic research before just leaping into the fire. Basic retail skills are much the same no matter what your business. If you take proper care of your customers, you have a fighting chance.
If not... you'd better have a short lease.