Sorry about your brother. Wish I was closer to help you out.
If you sign up for a Gunbroker account (free, and you don't have to ever use it), under the "Advanced" tab you get access to the "Completed Auctions" section where you can see what guns are actually selling for.
For example, you'll be able to see that this 29-2, with case, just like yours, was re-listed eleven times with a "buy it now" of $1,110 and no one even bid on it. He finally listed it starting at $.01 (one cent) and it sold at $1,150.
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=487089105
Your "gut" feel of $850 or so would be a good price which should sell the gun almost immediately. If you're willing to sit on it longer and put more work into it (list it on national websites, deal with the shipping hassle, etc), you could probably get a few hundred dollars (20%?) more.
I look at a LOT of guns and buy a LOT of guns. I'm not a collector, but an accumulator! General idea below of what would be "good" prices around here for a private sale of a gun in "excellent" to "like new" condition and sell the guns pretty quick. I'd ask about 10% more and let the buyer beat me down so they feel good:
Colt Commander - $700
Ruger .22 - $250
Ruger .357 - $400
S&W .38 - $350
S&W .44 - $850 - one EXACTLY like it (8 3/8 Nickel 29-2 with case, etc,) has been on the local Facebook gun trading site for $900 for about a week now - I've been tempted to buy it to go with my nickel 29-2 6"!
Ruger M77 .270 with scope - $400, depending on scope - again, one EXACTLY like it on the Facebook page a few days ago for $350, but it had a Leupold (expensive) scope on it. It sold within 5 minutes, I would have bought it if I had seen it first.
870 Express - dozens of them in pawn shops for $250 - $300
Romanian .22 Trainer - I have no idea on this one.
Most of the used guns around here are sold on Facebook sites these days. You may want to have some internet savvy young whipper-snapper check out the local gun pages for you if you're not into that kind of thing.
A shop is going to need to make a significant amount on each gun, so their offers will be much lower. Up to you to decide if the hassle of personally selling them is worth the difference in price to you.
Good luck!