$340 isn't a screaming deal, but it's not bad.
I have four .44-40's with the post front sight like Grant D's. One was $431 w/shipping & transfer fee in '09, one was a straight across trade for a ten year old G26 with a lot of holster wear that I paid $459 for in '99, and the other two were acquired in '06 as a package deal along with a stainless Vaquero .44-40, belt, holsters, some ammo and a couple hundred pieces of brass for $630. That was a pretty sweet deal, as the Vaquero alone will bring nearly that much now.
The .44-40's don't like Remington brass - the rims seem to be a tad thicker and most will drag on the recoil shield somewhat. All four of mine eventually developed a burr around the firing pin hole that needed to be stoned off as the primers would drag on it. All four also shoot about 8" - 10" high at 25 yards, so when I used them in Cowboy Action Shooting, I perch the targets atop the front sight and it works out fine.
