5k is very low, i would buy one for use and 1 for spare at that price.
hard to guess, i would say it around 15k minimum, and under 50k as maximum.
there is one M for sale on Twin Mall for 50k, but that is there since months (i can see it since summer ofc) probably since years.
As the item is very rare, depending on if you own and want to sell or nobody selling and you looking for buy one, i could imagine anything between 15k and 40k as a valid price.