I ordered nophead's Mendel90 kit (which he managed to ship to the US in 2 days flat). I was very impressed with the care taken in the every aspect of the kit, from the packaging to the parts, printed an otherwise, and the build directions. Very thought-through and meticulously executed.
I was able to assemble the machine with only occasional head-scratching and extended meditation when I didn't understand something (most of which would have been avoided if I'd read more carefully and paid better attention to the drawings). Once or twice I had to go back and do something over when I realized I'd been an idiot and done something wrong. My worst error was stripping a few tiny ball bearings out of one of the LM8UU linear bearings when I inserted a smooth rod, apparently with the finesse normally associated with a chimpanzee shoving a stick into a termite mound. Amazon.com came to the rescue with a replacement.
I did run into the small issue of the ATX power supply I purchased not quite fitting the provided bracket, but a couple of zip ties are holding it in place until I can print a modified part to fit.
The first print went pretty well, considering I had no idea what I was doing at any step of the process. I look forward to making a lot more errors and learning what can be done with the machine. Many thanks to nophead for his design and for a great kit.