@kaia @lain Depends if you are buying them to sell as coins or buying them for the metal value.
I mentioned the other day, but the best buy for metal is to just buy metal. Pennyweight jars of 24K casting shot are priced about 3%-4% over spot, which is pretty much the closest you can get.
You can resell it to any refiner and usually recover 98% of spot if you are willing to wait a day or two for the money.