About a year ago, you could shoot 6.8 basically for free.
S&B had good ammo for $5.99/20. It was accurate, brass cased, boxer primed, with really good brass.
At the time, SSA once fired was .35¢ , and everything else was .30¢. So, 20 x .30 = $6.00
So you could shoot it, sell the brass and have really nothing invested in it.
There is still ammo out there, good ammo, for $7.99 a box, and so you're only paying $2.00 for 20 rounds. that's cheaper than XM855 or Wolf, or even steel cased .223 or 7.62x39.
Of course if you reload, that works to cut costs as well.
Now I will admit, I was forced to sell all my guns at tax time due to major mistake in my property taxes, overcharged by over $2000. When they fixed the error, I bought a Tavor for me, and a AK47 for my son. My ARP 6.8 is still at the dealer for sale, because I haven't been back to pick up the AK, and I have mags, hand loads, components, factory ammo, dies ,etc, to take to him. Actually hoping I'm healthy enough to go tomorrow.
Anyway, what I was getting at is that I've been out of the 6.8 game now for a little while.
OP, I wouldn't sell anything right now, wait and see what's going on with the election. I don't think I'd sell the Arsenal anyway ( sold my SLR101s many years ago and have always regretted it ), or the 6.8s. I'd just save up for the other rifle. If you're looking for a hunting gun, the prices will likely stay flat or drop if the military type rifles go up, because they won't be able to move them near as fast, plus, deer season and most other big and medium hunting seasons have started, and people have bought for this year. They'll naturally drop a bit anyway and go up before next season.