A suggestion, top quality no B Shit service, maybe rather than having a huge amount of stock, a wide range of catalogues for people to choose from. Get the stuff in on time and fitted correctly.
I know my local mechanic will get stuff in, his prices are the same or sometimes a bit higher/lower that what I would get them for, but the service/knowledge is always top notch, that's why I always go back.
just my 2c worth
Best wishes with the new venture
Rgds
gerry