Gauss is not as valuable this wipe as it was before , not only because caps are much more harsh to get but as well of the buffs sniper/laser rifle has received. Though still a very good and efficient weapon , but it just doesn't have the " kick " it used to have compared to sniper rifle. Another thing as this season goes on , over time gauss pistols will loose their worth because those pistols are just going to pile up. That's why i'm personally not willing to bid high for obvious reasons stated above.
The optimal minimal starting price would be around 16-18k and then it would of course grow , if there would be any interested buyers at all.
I bid 18 k for only one gauss pistol with ammo , that's my starting offer.