Not a medallion, but there are wine corkstoppers which look exactly like the medallion Geralt wears. If you're a wine drinker and an enthusiast of witcher collectibles, I'd highly recommend it
https://www.amazon.com.au/dp/B076MD6P5X/ref=cm_sw_r_apan_glt_fabc_B694DKRQNVDE9KW1QD0G
A little pricey and it sells out semi quickly, but I managed to score one and I'm a big fan