Adding to the US Mint proof set value is the introduction of the Sacagawea dollar. Three separate options of proof sets were available from the mint in . ROYAL MINT UK 10 COIN PROOF SET IN HARD CASE WITH COA. £. Click & Collect. £ postage. Product description. The United States Mint Uncirculated Coin Set includes two envelopes of 10 coins each, with coins from the United States States Mint at.