I think it has been mentioned a few times, but probably worth it again. If you can, in any way, afford the plug in play system you will be glad you did. I did the build-your-own CNC one at first, and did get it to work, but then I opt'd to get the plug in play system with my new CNCRP and I couldn't be happier. The amount of time, frustration, and energy I saved on literally plugging it in, and turning it on, at least for me was definitely worth the amount I saved in parts. I had one small problem that CNCRP took care of immediately that didn't impact operations, it was just a missing screw. From cabling to powered on you can probably be going in under 30min or less. CNCRP gives you all the files and settings you need for Mach3 as well which was a huge time saver for me.
CNCRP even sent out a patch when Windows broke Mach3.
Except for windows being windows, when I go out to start the CNC, I know it will fire right up and just work. And if there is a problem, I know I can contact CNCRP and get immediate help.
Sometimes I look at it and think about the $$ for a split second, and then I remember all the hours I spent fighting with my old one, smile, node, and let it do it's thing.
You are right, it is a lot of money when you think about it, but at least for me I found it totally worth every penny.