It takes time (about 8hrs for me, working slow), but isn't difficult if you take your time and can solder or learn to solder. You need a soldering iron ($25), soldering station or holder (something safe to set down the iron and a sponge to keep the tip clean - $7-10), multimeter, wirecutters and strippers (often the same tool), needle nose pliers, solder, flat head screwdriver, wood glue, magnifying glass and tweezers also helpful. Can't think of anything else essential. A drill is helpful to twist the wires, but not essential. And sandpaper, paint, finish, and sealer if you want to pretty up the chassis and wood bottom. So how many things do you have already? And for those things you buy, how many can you use later for other things.
For me, it was worth it to build myself and put what would have been spent on assembly towards speedball upgrade and tubes. Plus, how many things that really sound great and you'll use for hours and hours can you actually build with your own hands?
You know there's a 15-20% discount if you order Crack plus Speedball before Sunday night. . .