Something is worth just as much as someone else is willing to pay for it.
It all depends if somebody is completist, are they collecting purely for the love of the movie/character..or any other of many reasons.
I personally wouldn't pay much more then shipping for it, because I live in Croatia, and it would cost me a lot of money just to import it..and I already have Russes Flask which I consider to be perfect replica. I really don't care for a quantity number in collectibles, as I collect ONLY things I really really want, and won't be reselling ever, I don't care for the aftersale value.
I have a friend who is quite the opposite, he collects rare stuff, stuff that will go up in price in some time, so he can resell/trade for something more rare. He'd be interested in this flask much more then in Russes replica..
My point is, you should put this on eBay and see how it goes if you're thinking about selling it..if not, just enjoy the piece for what it is, and don't bother about the price
(if timing is right and it gets enough attention, I'm sure it could catch pretty nice sum of money
)