Hi Hoplino
I think that an ordinary Osprey is classed as collectible as they've been out of production for years so a Supertarget would be even more even more desireable as they didn't sell in huge numbers
As for a valuation- I'm hopeless in that department but if you link to a couple of decent quality pics, the experts on here will give you a good guideprice i'm sure
Welcome to the forum
John