There are loads out there it just depends on what you are willing to spend.
You have to name a few,
Sly pro merc
Deadly wind
Stiffi
Planet eclipse
unitec
CP custom
Dye broomstick ultralite
Some make carbon fibre others do not. I would say if if you like a barrel and spend a bit more it do, even if you sell the marker at a later date the barrel will/can stay with you, unless you change to another marker that has a different thread.
If you read some of the forums in the states they talk about the size of the paintballs getting smaller.
I would go with some thing like the .691/693 as most site the rec balls will be ok with these barrels, if you are playing sup air etc the tourney paint is slightly smaller and I normally use a .689 as this is how my barrels are made.