There are probably just 3 of them in existence by now (bp.tf says that too), definetly will be more in the future. I own one myself so I will try to set a very fair starting price.

Only 2 are for sale on SCM:

https://steamcommunity.com/market/listings/440/Unusual%20Bumble%20Beenie?filter=snowblinded

https://imgur.com/a/fSVuQlO

The price of the cosmetic is moving around 116$ to 240$ at the moment, but the sellers seem to be pricing it to a lower part of the value.

Their prices in keys are 50 and 74, so average price would be around 62 keys. It's also an all-class cosmetic item.

There is nothing else really to be added since it's a new cosmetic item with a new effect that just came out. I haven't put mine for sale because it doesn't have any price yet, so I'm trying to give one to it. I really hope this is a very fair price suggestion.