I've always wanted to try a Gimbal, but never wanted to fork out $300-$500 for the ones I liked. With my 600mm equivalent f4 on pre-order, I've been looking at them again. As much as I want one, it would only be used occasionally, so i decided the "best" wasn't necessary. So for the heck of it i checked out low priced ones on amazon. I decided on the Mcoplus, linked below, only $75! I received it last week and I must say I'm pretty impressed. It is really well built and functions as described. I'm sure its not as smooth as the expensive ones, but certainly well worth the $75 if you want one to dabble with one. I find it to be very stable and will certainly give me great stability when tracking BIF, or anything else. A wee bit of play, but if you snug it down it's pretty solid. I just thought I'd share this in case anyone has considered the less expensive options. It is inexpensive, but not "cheap", excellent for the money!
Amazon.com : Mcoplus Professional Heavy Duty Metal Gimbal Tripod Head with Arca-Swiss Standard Quick Release Plate for Digital SLR Cameras : Camera & Photo
Amazon.com : Mcoplus Professional Heavy Duty Metal Gimbal Tripod Head with Arca-Swiss Standard Quick Release Plate for Digital SLR Cameras : Camera & Photo