If it's an auction, my method is to start at the lowest price I'm willing to sell for, or maybe just a touch lower to encourage the suckers. Set price? Whatever you think the market will bear if you're not in a rush. You can always go down if no one bites.
If you feel the rifle alone was worth what you paid for the whole package, you can afford to be a little generous. I never try to sweat the last dime out of stuff I sell, just a fair price for both parties. That way everybody can feel good about the transaction. Since I don't care for silver riflescopes, I can't say what it's worth to me.
