Go to Amazon if you're interested in purchasing a cheap copy- I just got a brand new mint set with CDs (not tapes) and the primer for $50. With seat deposits due, I defintely didn't want to pay $150 for this thing...Last I checked there were other people selling them in the range of $44-$62. Just be sure to verify what is included- some people are just selling the primer; some are probably selling an ancient copy...I made sure to ask the edition/year, what was included, and the condition.
Good luck.