But..buut... argh god my head, why would you buy it for a chance instead of just buying the actual item.
What I'm saying is, what is the whole point, just ID it, sell it. End, no if's or buts, just do it.
As mentioned, its gambling.
Identified item is worth 1000g
Unindentified is worth 10g
Cost to vendor is 1g
Seller gets 9g more, buyer potentially gets a 1000g item for 10g.