Those are a dime a dozen, You can go with the brand name stuff but weight issues are usually solved by a single counter weight that you move up and down the arm.
I have allot of britek equipment, Cant go wrong with them
BRITEK DELUXE BOOM SUPPORT WITH STAND SYSTEM , 98.00 - eBay (item 220375429231 end time Nov-04-09 19:02:20 PST)