Or for much much much less than an astrotrac you could try this, which debuted at NEAF
http://leo-optronics.com/
(look for the "music box" EQ drive)
Warning-I dont own one have never seen one and dont even know if it is commercially available
other better established alternatives to an astrotrac are the Kenko sky memo
http://www.sciencecenter.net/hutech/kenko/skymemo/
or the Vixen GP2
http://www.optcorp.com/product.aspx?pid=439-1287-11294
or the Takahashi Teegul
http://www.takahashi-europe.com/en/TG-SP2.php
or this thingy
the Hoshino CD-1-which Peter Tan in Hong Kong lists on his website
http://www.eyebell.com/guide.htm
(you can get google to translate if your japanese is like mine, somewhat wanting)
nothing is particularly cheap-except the Music Box I suppose
The astrotrac is the most portable and carries the most load, but its not cheap
Narayan