They're really not hard to do yourself. I just installed a new one a few months ago and really didn't have any problems at all. But, depending on where you buy the dishwasher, they will likely offer an installation deal as well. Plan B might be to just ask some of your neighbors for a plumber recommendation if you don't already know of a plumber that you trust.
If you're fairly handy it's not a difficult job. But, don't do it yourself unless you're totally confident you can do it right. The consequences of a poor installation are not pretty.
Yeah, I had a garbage disposal replaced once and the drain line for the dishwasher feeds into it. The installer left the drain line detached and it caused a hell of a mess the next time that I washed dishes.