Four rare coins to 'make you retire' including £130k penny and ultra-rare 50pThese four rare coins could help you bank an early retirement as one of them could sell for an eye-watering £130,000. Whether it's a super-rare 50p coin or even the "rarest coin in UK history", some are undeniably more valuable than others. ‌Finally, there's the Kew Gardens 50p coin - but specifically the gold variant. The collector concluded: "A gold-proof Kew Gardens 50p has recently sold for £6,800 at the Royal Mint online auction. "The ultra-rare version of the sought-after Kew Gardens 50p was estimated to fetch between £5,000-£6,000 and did end up selling for thousands."