Hi Peachy. Must have lost this thread amongst the masses.
Do you absolutely have to have Goto? You could get a mount to do what you want at less than your limit, IF it doesn't have go to. At your limit you would find this mount
http://www.myastroshop.com.au/produc...asp?id=MAS-042 a ripper. If you must have a goto then you would be looking at something like this
https://www.bintelshop.com.au/Product.aspx?ID=7529 . It doesn't have the capacity of the HEQ5 though and probably not the guiding accuracy either.
Even for widefield if you are going for a reasonable length of time it would still be advisable to implement some sort of guiding. It will depend on the focal lenght of your lenses, the accuracy of your polar alignment and the periodic error of the mount how successful unguided imaging will be.
If you are going to autoguide then any refractor of similar focal length or shorter than your imaging scope will do. If you are going to manually guide than you need around 1.5x the FL. Using a 2x barlow would be enough with a shorter scope.
For a first imaging scope that is extremely good value for money, you could hardly go past the Orion/Saxon/Skywatcher ED80 (all the same scope) though the 66 Williams is reportedly a fantastic scope. If you have a look in the Icetrade forum under Telescopes you will find a WO 80 apo for sale at a great price.
If you are starting on a tight budget I'd suggest a small 60-70 mm refractor (Orion 80ED if you can afford it) on a HEQ5 mount, piggy backing your canon for widefield. If you then decide on getting a planetary camera like a ToUcam or better yet a DMK or DFK (colour) then you can get adapters that will fit canon lenses to it. With a 2x telextender a cheap second hand 80-200mm zoom lens becomes a 400mm autoguiding scope.
Anyway there are a few ideas to think about.