What you are talking about is CAM Computer Aided Manufacturing. For programming a CNC machine, you may need both if you are designing the part and machining it. Many of the programming systems are CADCAM, but “programming system: generally infers strong in the CAM part of it and light on the CAD ( it may even not have a CAM part, but most do today).
Some of the cheaper software’s are buggy and have problems but in general, they work fine.
What software to start look at? I would say start in the price range you can live with, $600 to $2000 as the cheaper ones with a few even lower.
I Bought one a few years back that didn’t work for me, I constantly was fighting it. Just recently I bought a new one, but only after using it for a 30 day free trial. Everyone of the ones that you will read about here in the forums will have a 30 day free trial period. Some even give you for free a lower version of their software. You might want to start with one of the freebee’s that you can upgrade later.
I have used only three out of dozens of CADCAM programs out there. EZCam (5k) works well but higher cost, BobCad ($600.) cheap. but very buggy and not my style but a number of people us it. Visual Mill ( around 1K) CAM strong CAD weak.
I currently use Alibre V10 Pro packaged with Visual Mill Pro. (about $2.6 to 3.6K).
Steve