I just installed the viper 791 system in my friends tacoma, saved $250 as well. As long as you can read wiring schematics and are good with electronics it's not too bad. Just use common sense. I have electronics experience and it took us about 6 hours to do the whole install. Plus the viper systems is one of the hardest to install yourself. The commando system is a lot more user friendly. Also, it's going to be harder if you have the stock toyota alarm because you are going to have to wire in for a disarm pulse to it, or remove it completely. Won't really add difficulty so much as time. If you need any help you can PM me too I can try my best to help yah. I didn't do it for a living like live42day, but I know electronics.
As long as you are good with wiring it won't be to bad.