If you wait long enough and endure the sales calls, the price for BobCAD-CAM keeps getting better until you breakdown for fork over $650 in my case. I started with Version 23 and upgraded to Version 24. If your new to BobCAD-CAM then you'll want the training video set too. It's gotten much better in V24.
The Post Processor is a set of directions that BobCAD-CAM uses to transform it's g-code instructions into g-code instructions that will run nicely on your machine. If you have custom machine driven by Mach 3 like mine, then you'll need to download one of the "Mach" post processor files and possibly tweak it a bit for the way you do business. I started with the Mach3-Mill-NoATC_Rev2.exe post processor and then modified it. The "No ATC" stands for No Automatic Tool Change.