This being a TV product I assume it would be better than anything I could make myself. Is it any good for binos? What's the biggest size it could handle?
The TV mount is not really suited for binoculars. Telescope wise it will handle tube diameter of up to 90mm. The diameter of the optics it self can be larger (e.g. a 101 or 125 Borg with its 80mm tube diameter wouldn’t be a problem at all). It will handle up to about 10kg - 12kg, mostly depending on the tripod you use.
I hate to ask dumb questions, but how exactly does a scope attach to this mount? And will it allow you to reach zenith? (I assume it would be perfect for my Megrez; how much do you want for it?) I have a Manfrotto 055CLB tripod: I guess it's got the 3/8" thread, but I'll need to check.
Televue's website say that the pan-handle comes standard. Do you have that, and if so are you including it?
The scope will be screwed on with one or two hand screws (see the two holes with white surroundings in the picture). Those screws have the standard camera thread what your Megrez has in the L-bracket.
The zenith question... It can reach the zenith without the handle but not with the handle screwed in, then the handle touches the mount just before reaching zenith. For the scope it self is plenty of space to reach zenith and beyond. So there are two ways around this: First, you just unscrew the handle and use the telescope it self to steer it around (that is what I did, and you will find this way it is much easier to track if you use higher magnifications). As I you can see in the photo, the handle is not screwed in. Or secondly you get yourself a second handle bar in the right diameter bend it a bit.
The mount has a 3/8" thread to connect it to a tripod. I used it on the very same Manfrotto 055CLB tripod.
About the price... those mounts sell on astromart.com for around US$300. I know that I won't get this sort of money here in OZ but I would like to get as close as possible to this number... so just make an offer ! ! !