I use draftsight with is an autocad clone and the price is definitely right. You can download it from DraftSight - Free* CAD software for your DWG files - Dassault Systèmes and it will look very much like autocad and can even handle all its files. It is made by the people who make solidworks. You have to register it with a good email address, but I receive very little traffic from them trying to get me to buy more. Most of what I get is "hey we have an upgrade"!
Yes, it will work with Sheetcam as that is what I also use.
Art
AKA Country Bubba (Older Than Dirt)