I have the deluxe CNCFusion kit, and I have never been sorry I bought it. Sure, it is more expensive than run-of-the-mill ballscrews and nuts, but to me the peace of mind of not having to constantly be fighting backlash and inaccuracies was worth the extra cost. I realize not everyone has the $200-$300 difference laying around, and sometimes you just have to compromise to make the project fit the budget. But I certainly don't feel the additional cost of the deluxe kit is a waste.
If you know absolutely nothing about milling, you will definitely learn something in the process of making your own motor and ballscrew mounts. You will probably make them 2 or 3 times, and you'll get better each time. You need to be able to measure and cut things to a good level of accuracy; which is a skill you need to learn eventually if you ever hope to find satisfaction in metalworking as a hobby. The things you will need to cut, like bearing pockets and mounting holes, aren't magic - just be prepared to be disappointed in your early efforts and be willing to toss them out and start over; hopefully learning something with each iteration. There is no feeling quite like looking at a piece and knowing you made it yourself.
Any fool can buy perfection - but it takes a true machinist to make it; and isn't that what we are in this for? Look at it this way - you probably won't save much in the long run by making all your conversion parts over buying them. The difference in cost will probably be eaten up by scrap and by however you decide to value your time. So if getting productive in as short a time as possible is most important to you, buy the bolt-on kit. But if you are wanting to teach yourself precision and patience, and you value the learning experience and want to become intimately acquainted with your machine; build it yourself.
The risk is that you might find yourself over your head; and you might get discouraged and end up thinking this hobby might not be for you. If that's true, better to find it out now before you've used up a second mortgage to buy tools. But post here first before you give up - I think you'll find enough encouragement and experience to get you out of just about any jam.