I have the Manfrotto 055XPROB and it is probably one of the toughest and durable tripods available. I doubt carbon fibre would last as long.
My tripod was dropped into Eagle Creek this past spring trying to get to some remote waterfalls. The tripod was in the cold (50 degrees) water for TEN days. I found it on another trip. I also hike many MANY miles with this thing. A few buddies and myself were at the remote Ruckel Creek Falls in the Columbia River Gorge this past June, and we got lost. We ended up trekking basically up animal paths to the top of Benson Plateau (3600 feet I think). I used the tripod as a walking stick to assist with balance and such.
The thing is a beast. It fell down a talus slope, maybe 200 feet. Paint missing, but no dents. It has been in the ocean for prolonged amounts of time. I regularly clean it (take it apart and wash it out), and it works more or less like new
I think I paid $160 for the legs. I also use a 322 RC2 head that has been along for the ride. My first 322RC2 lasted 8 years. I only sold because it was getting a bit worn out. I think those are like $120 or so. I use a 1 series Canon on it with an 85mm 1.4 mounted to it, and it is sturdy.