Many vendors seem to strangely believe that you are somehow limited to selling back to them at a later time what you buy from them now. If so, find another dealer for someone telling you this sort of nonsense does not know the first thing about the thing he is selling. Precious metals bullion bars and bullion coins are not collectibles that need to be sold to special goldsmiths or coin shops. You may buy or sell them freely wherever they are offered. You may or may not want to sell back where you bought and it may be a nice to be able and re-sell to the same dealership at a later time, but neither any need nor any increased likelihood to do so. Rather, where you buy or sell is largely a matter of price.

Do I Have to Pay Sales Tax (or VAT or Similar) on Precious Metals?
Should I store my precious metals locally or overseas?
How Much Should I Pay for Physical Bullion?
Can I Earn a Higher Profit With Numismatic Coins?
What Is a Reasonable Premium Over Spot?
Should I Buy Bullion Bars or Bullion Coins?
Should I Buy Bullion Online?
Should I Buy Bullion Over the Phone?
Should I Buy Bullion Using eBay or Amazon Marketplace?
Is Confiscation of Gold a Real Risk?
Are There Any Reporting Requirements for Gold or Silver?
Should I Buy Vaulted Allocated Gold or Silver?
What Is a Monster Box?