In addition to the brand names mentioned in Post #6, I'll add Bentley MicroStation to the list, Probably a few $K to buy retail.

Here's an idea: Look around for part-time/evening classes at a local community college, courses titled 'Using CAD' or 'CAD Design', or something like that. Sometimes large engineering firms even offer night classes like this to entice people to become cad designers. The point being, sign up for a course and they almost always offer student pricing on some main stream CAD package used in the class. The CAD software vendors want people trained on their products, just like Microsoft entices students to buy Office at very reduced student prices.