You can build your own with some PVC T's and pipe. Join the T's together with short section's of PVC then make your uprights out of the same PVC about 12-14 inches long. Then depending on your boat several different ways of mounting solid. They work fine but I prefer a horizontal carrier like Mrdux has. Easier on the rods and lot less chance of breaking one. Check out the ones Creekslick on here builds. He is in the sponsor section. Or just shoot him a PM.
Proud Member of Team Geezer
Charlie Weaver USN/ENC 1965-1979