@GiGoGo I see that you are based in Hong Kong. So, what you want to offer is a combinations of these services.
1- Better prices aka less "premium" than your competition.
2- Offering Secure storage by partnering up with private vaults/storage providers or you can store it in offshore storage (away from the uncertain Hong kong/Chinese political climate) in
la freeport singapore for example and your bullion storage will be insured by most of these private vaults directly thru them or via third party insurer.
3- Liquidity. people who buy gold will want to sell it some time in the future and you want to offer this service by buying gold from your customers via BTC/crypto or via fiat by partnering up with OTC exchanges like
Genesisblock HK for example (you give the exchange the BTC/cash via their OTC desk, and they will give you the cash/BTC for your customers. this could be handy if your customers opted for Fiat/BTC as a payment).
4- Privacy. Of course, you should emphasize on these elements. Privacy, confidentiality...etc. but by actions and not empty talks. What I mean is:
A) from the financial point of view, offer crypto for payments but encourage people to use private coins (i.e. monero) by offering discounts for people who opt for private crypto as a payment option.
B) from the legal point of view. Encourage people to purchase thru corporations/trusts and ease this process by partnering up with the top offshore company/trust providers and offer discounts for people who use your "vetted" service providers through your website.
So now your website/shop is a one heck of powerful place for exchanging crypto to gold and vice versa offshore.
Also don't forget to market your website thru Crypto social media channels and specific targeted forums that will need your service (like this forum) and the likes and create content for your website through blogs, YouTube videos...etc.
Good luck!