I use AutoCAD a lot for work (Windows based). I downloaded AutoCAD 2012 for my MacBook Pro and so far I'm really impressed. They have an LT version available for Mac as well. If all you need is 2D it's great, and quite a bit less money. I've tried TurboCad and one other (the name eludes me). I found it difficult/time consuming to learn each interface, as they differ quite a bit from AutoCAD.
Kris