Hi DrCortex,
The most spoken of here is Wildcard's ArgoNarvis. The unit + encoders (depending on the scope) will set you back around $1000 - probably less.
The beauty is that you can take the unit to your next scope and purchase the relevant encoders to suit that scope.
2ndly its Australian made, delevoped, designed.
http://www.wildcard-innovations.com.au
There is also the Skycommander to my knowledge.