For most of my backcountry fly fishing in Yellowstone, I use a 3 wt 8.5 ft 5 piece Stowaway Rod (Cabela's) which is in the $100 to $130 range I think, and as far as lightweight 5 pc rods go, it's on par for weight, about 3.5 oz.
I pair this with a Sage reel that was a gift to me, a 3100, which is 2.7 oz, and one of the very lightest machined aluminum reels on the market. The only lighter one I found was one from Hardy at 2.6 oz, but it held a lot less line.
BackpackingLight.com is launching a new section in the store here this spring - probably March - and we'll have some really neat goods sourced specifically for the backcountry fly fisher, including a very light rod and reel combo tailored specifically to small stream fishing, and a selection of very nice quality, but not outrageously priced, 5-piece fly rods in the 4-5 weight range.
We're also adding another foam fly box (smaller and lighter than the current one) and some pretty cool "ultralight" accessories as well...stay tuned!