MJB Monetary Metals were coins minted at the "Mulligan Mint", which only operated for a very short time but were known for super high-quality rounds because they were minted using old Denver Mint equipment that they had aquired in auctions. They only operated for a very short period before shutting down due to a large "missing" shipment of silver, so coins minted by Mulligan Mint will very likely fetch a higher numismatic value simply because of their extreme rarity, in the future. They are highly counterfeighted, particularly the copper "circuit board" bitcoin logo coins which made it onto so many magazine covers, but they also include the "very first" bitcoin rounds to ever hold the bitcoin logo, even before Casascius coins, as noted in the encyclopedia of physical bitcoins. So those onese are super highly prized and they sell for upwards of $300 for a single GRAM of silver.