Originally posted by soccerjoe5 I believe even the Manfrotto 055 series will be enough (It can handle up to 15lbs I believe) which can be had for $150 or less. Very solid support and fantastic value.
As mentioned above though, the head will be much more critical
No way. I never would use my 055 with such a load. I imagine that a lens of that weight will also excert considerable torque.
I would buy a used big Gitzo aluminium tripod (my old Gitzo Studex would probably be too small) . Alternatively wooden tripods would be a good choice, either dedicated photo modells by Berlebach, Wolf etc. or surveyors tripods, but these are really heavy (have one for a telescope...)
You will have more of a headache when it comes to a good tripod head for such a lens. I would either use a gimbal mount or a really good video head. Video heads are considerably cheaper than photo heads, as they have one axis less (2D instead of 3D), but heavy lenses are usually rotated in their mounting ring to switch between landscape and portrait format, so the third axis is not necessary. Otherwise the big Manfrotto gear driven head might be good choice.
While writing about video heads: a video tripod might also be a good choice - obviously not of the small variety...
Ben