APMEX accepts paper checks through the mail. Old school style. You lock in a price when you order and then you have several days to mail a check. The price can rise every day but you’re still locked in at the price from days earlier. I use them a lot but any of the well known sellers are trustworthy. They have a good selection of coins, junk and bullion. If you can buy local go for it. I don’t because online sellers are the cheapest.