It took me about 3 weekends (with a lot of interruptions) to build mine.
The software provided for it is open source.
You can find all of the instructions and links for the software in the link below. http://www.k8200.eu/
Took me about two evenings, would have been quicker if the instuction suggested creating the wiring looms seperate to the assembly and then introducing them rather than creating them within the assembly.
Hats off to those who built it in 12 hours. I didnt count, but I think it took me closer to twice that, and usually I had someone assist me (often handy to have a spare set of hands). Time well spent though, there is no better way to learn exactly how a 3D printer works than building one.
I think the average time will be about 12 hours (= two afternoons, two evenings). You will need some specific tools like a soldering iron, special pliers, etc, so make sure you have those before you start.
Finetuning, repairing, upgrading, is kind of part of the experience and part of getting to know the inns and outs of your printer.