When you say AutoCAD do you mean the full blown version? There is a LT version that runs about $900.00 retail from their site. It does 90% of what the full version does, but doesn't run scripts.
I haven't had personal experiance with any packages other than AutoCAD products myself.
Turbocad is the same price as AutoCAD LT.
There is Intellicad which is cheaper but I know nothing about it.