As you found out, none of the cheap tripods are very good. You need to be even more careful with tripod heads. There are lower cost tripods in the $100-$200 range from Slik that are of for occasional use on a smaller DSLR and lens, but when you start getting 3 lb lenses, the cheap tripods and heads will not do a very good job.
A head is probably even more important than the legs. Good tripod systems have separate heads and legs, but sometimes come with a combo deal. The standard mounting for head to legs is a 5/16 bolt. don't get one setup for 1/4, its too weak.
The other thing to look at is the camera QR plate system. Arca Swiss Compatible QR plates are THE standard, Manfroto makes more than one style, so you can end up with one style on one head, and another style on a monopod. Watch out for this. You can get a Manfroto head with Arca Swiss compatible QR plate!
Its best to just buy heads that take Arca Swiss compatible QR plates, this lets you use many different accessories, and you do not have to keep changing plates. In some cases, you can modify a head, but that's wasting money.
The units recommended by those above will probably be fine, but watch out for the QR plate.