Yeah good idea, only deal with non-reversable payments like Cryptocurrency. Also don't limit yourself on that and sign yourself up to plenty of exchanges. Some rather send via Coinbase email or Wex code or whatever. You'll also want to make yourself very easily available so Website, Discord, Skype. You'll want a quick turnaround for the sales and also you'll want to ensure pricing is the absolute best. Only easy way of ensuring that is buying a bulk order on like a Friday night 1bill and shift that over the weekend. Scale as you grow.
Also ensuring you're using a method of obtaining lvl3s and IPs where they cannot track you.
Thirdly getting to know middlemen across the various sites, get to know their time zones and so they can help you seal a deal.
That's my 2 cents, one day I'll do a proper gold shop