Hi.
I've been using ViaCAD 2D/3D and CamBam together for the last year or so and it's a marriage made in heaven, as far as I'm concerned. ViaCAD is $99 and CamBam is $149, so they're well within your price range, and I think wonderful value for money. ViaCAD does excellent DXF and STL file exports (amongst many others) to CamBam and can switch instantly to a 2D only mode, which is absolutely ideal for drawing the profiles you're going to need for most of your cnc work. Both of these programs are very powerful and both have strong 3D capabilities. The combination has, more or less, caused me to stop using Dolphin Partmaster - which is itself a good piece of software, but probably outside your price bracket.
Cheers.
Martin.