Let me add that I am a Latin teacher with little technical knowledge and I have built a lot of these kits. The easy ones and the complex ones. You can do it. Just practice soldering on some spare parts or some cheap parts from Radio Shack. Watch a soldering tutorial online, its not hard.
The manuals are the best in the business, truly. If you can tell a resistor from a capacitor you can easily do this, and from looking at the underside of the Crack amp, this is the one to cut your teeth on. The manuals have great instructions and Doc's hobby of photography makes the manuals incredibly well illustrated. The pictures are clear and let you see if you have done it correctly. You need a soldering iron, solder, needle nose pliers, wire stripper, some screw drivers. Can't think of anything else off the top of my head. It really is fun to do and being able to have people listen to it, be amazed, and then you say you built yourself and it only cost $200. Well, its about as much fun as you can have in audio.