If you need quite a few to start with , OPI and Morgan Taylor do the small sizes in packs of 4 or 5 minis.
China Glaze is very good and not expensive for full size bottles.
I buy the colour I want , I don't stick with one brand only, but as it is your business you can do what you like.
I use Cuccio and have a few Orly so I have plenty to choose from.
Happy shopping!