It's not hard to install a suspension lift. You will need some tools... a good set of 1/2 drive sockets and wrenches, a breaker bar, some big open end wrenches... 13/16, 15/16, 7/8, probably a few others I am forgetting but smaller sizes. You will need a pitman arm puller and a... dammit... I forgot the size. Less than 1 1/2 inch socket for that. Make sure you get rear leaf springs, not the blocks.
Like I said, it's not hard, you just need some tools and some time. Plan to do it over 2 days so that you can take your time and get it right. Don't do it in a big hurry.
To me, $600 is a lot but I've never paid for a lift or anything to be installed. I look at that $600 like you could put that towards some sweet shocks, or tires, wheels, whatever.

 

**** that is a good price if you are talking about the bds. i priced the bds in mass. and they quoted me 2000$ for the long arm kit with rear springs not blocks. and like 850 for the install witch is a rip. i put my 6in lift on my silverado (IFS) now that was a pain in the a$$ nothing fit right go figure (superlift) nothing a torch and welder couldn't fix as for the install if you have the floor jacks, jack stands ect.. and basic mechanic knowledge then go for it. word to the wise 3/4 in impact works wonders on the stubborn bolts