He's running a business, and would not offer something unless he thinks he can make a profit on it, so maybe it's worth more than the $800. So it's up to you to decide to either:
- Take the guaranteed $800.
- List it yourself at $1 no reserve auction, take the gamble that there's at least two people who might want it to outbid each other past $800, or that if noone else notices the auction you might get less.
- Stick it up for a 'buy it now' of something like $1500. It might take a while to sell at such a high price, could take a year, but eventually someone will see it who's willing and able to pay that much.
If you really need the money and need it quick, take the $800 (you can do legal/safe things like end the auction early and send him a second-chance offer at $800, you'll still pay ebay/paypal fees but you're paying for their protection), if you want to gamble just list it no-reserve, or if you'd rather hold out for more money then post it with a higher buy-it-now price.
But yeah, a professional appraisal sounds like a good idea first, maybe the frame is real gold?
ps, those dogs are just pooped after a long day, they're the type of dogs you hunt with, not the type you hunt.