The materials and craftsmanship are going to be subpar. Stitching is what you need to pay attention to, along with zippers. There is a reason why the Voodoo bag can offer the "same" features as these high end drag bags, but for a quarter of the price.
Careful. Often they use good materials, so it has Cordura and YKK and so on, with these labels prominently displayed. But that does not mean it is sewn well. Here's a nice (long!) discussion of what you get out of quality built stuff, vs not:
http://www.lightfighter.net/topic/what-is-quality-picture-heavy
The other thing is supporting designers. MANY of these are knockoffs, so they also save money on not iterating on the design work. And, the original designers do not get as much payback for all their work.
Back OT, I have a few things, but for the precision rifle almost always use an old school Eagle "Sniper Rifle Case and Shooting Pad."
http://www.eagleindustries.com/products/detail.aspx?id=69 I don't seem to have a photo of my gun in the bag, but here's a previous iteration of the rifle in shooting position:
It is lovely in every way, just unfold, unclip, and start shooting right from it. But, best for range, or when heavy packing in a vehicle, etc. Not as slick for carrying as something like tossing into the Erblestock scabbard.
I am shortly going to cut down the barrel a but, and have recently gone to a folding stock chassis, so will likely change entirely to... something else. So following this discussion and others closely to get ideas.