Most people think of Gold bars or Silver bars when talking about bullion. This is only one form of bullion.
When dealers talk about bullion, they generally are including bullion coins. These include-
Canadian Maple Leafs
Mexican 2 through 50 Peso
Isle of Man gold,silver or platinum
Generally, the term “bullion” includes any coin which is readily deliverable and trades based on the daily price of gold. Only a few items need to be reported upon sale, so don’t allow dealers to talk you out of buying bullion coins because of reporting requirements. The newer U.S. coins such as Buffalos and Eagles are specifically defined as numismatic coins in the legislation that created the mandate and they are not reportable by the dealer you sell to. However the IRS requires you to report profits on ANY numismatic or bullion item.
These are a small sample of bullion coins that American Federal both buys and sells.