Are you after a transportable (I wouldn't say portable) or a fixed observatory mount ? Many not mentioned in your list such as
http://www.astro-physics.com/
http://www.sungazer.net/ap900.html
http://www.mathisinstruments.com/
http://www.alpineastro.com/COMEC/10M....htm#centaurus
Parallax Instruments..
just for starters..