Good back bar

I’m thinking of going solo and am so lost with back bar, i’m not looking to do retail, therefore am I able to purchase product from any brand without getting their education and registering my business with them and just use it on clients without the wholesale price? I’m thinking of using dermalogica because i’ve been using it and it’s convenient to get, but ive read there’s minimums, I was just going to buy it online out of pocket like a costumer rather than professional and use it on my clients, is that possible? Also does anyone know of any good korean professional skincare I can use on clients?