Depends on if it's a new custom stock or an 80s/90s one.
Original ones are always going to be more sought after. If its a modern stock then you can buy them readily from CS stocks in sheffield for around £200.
Then it comes down to the action. If it's a venom one and glided, then you can increase the value.
Unless you've seen it first hand and verified what it is then throwing figures about is irrelevant.
Fozzy