I'd feel comfortable recommending the kit that's made from Ahren's parts even though I don't have one. Plenty of people have gotten their machines and are satisfied. http://www.finelineautomation.com/st...?tag=FLA100-00 You'll end up spending another 500 or so on electronics but you'll end up with a very capable machine. I recently got 3 sets of Ahren's rollers and am very satisfied with them.
I'd definitely get a kit before trying to DIY on everything. The less you have to fabricate, the easier and faster it'll all come together. I've gone completely DIY on 2 machines. I kinda feel like I've wasted more time than anything else on them over the past year. I have learned a lot though and am feeling confident with revision that I'm currently doing.
I'd say my best investments have been, G540 driver, 80/20, Ahren's linear components, and my pillow bearings. Tool wise, parallel set, drillpress, digital calipers, and so on.