before selling it back leaves you level.
Three things the spread quietly decides.
Gold could have a spectacular year and you still lose money, if you bought at an 11% spread and sold inside it. The spread is the hole you climb out of before any gain is yours.
A one-ounce coin might carry 4–6%. A tenth-ounce can carry 12–15% for the same metal, because minting a small coin costs nearly as much as a large one. Starting small is the expensive way to start.
Buy prices are on every homepage. Buyback prices are buried, and some dealers will not quote one until you ring them. If a dealer will not tell you what they pay, that is the answer.
This is arithmetic, not advice. It tells you what a given pair of prices means. It does not know whether gold will rise, and neither does anyone else. Storage and insurance are included because they are real costs people forget — tax is not, because that depends on you and on the coin. UK-minted Britannias and Sovereigns are sterling legal tender, so under TCGA 1992 s.21(1)(b) they fall outside capital gains tax entirely. Bars do not, and nor do foreign coins like Krugerrands. Check your own position.