Delicate one this as the stock is badly damaged. I would not value it more than £60 to be honest if someone wants a use-able cheap plinker.
Its about that in spares as the stock is often the biggest value when in reasonable condition. If the stock hadn't been damaged I would have said about £90 bearing in mind the metal work is painted and would require work. Good ones will go for a fair bit more and £200 plus for a minter with BSA etching clear.
The problem is they are not economical to do as a project, and usually cost more than they are worth.I've got a few Airsporter projects on the go now.