Originally, I had planned on getting a Pelican or SKB hard case, and having the foam cut around all my parts and accessories so I could feel like some movie-style assassin, but they're $150-$200 and up. Worth it if you're going to be flying w/ them, or have some heavy traveling to do, but otherwise a soft case for $20-$30 does the trick for simple drives to the range. Plus they take up so much less space in the car/closet or whatever.
I ended up w/ some no-name bag from the local gun shop for $30. Plenty of room for the rifle, room for 4 mags, large carrying strap, pocket for targets/etc.