What are you looking to buy/install. I purchased my Furuno stuff from Mid-Shore in Cambridge MD, But installed it myself after they told me 2 guys, 8hrs each, 2 days for the install. That's 32 man hours at $85/hour = $2720 to install a fishfinder in a boat that was already rigged and has rigging tubes.. I told "NO Thanks". It took me 4 hrs to pull the old stuff and install a new combo fishfinder and a new transom mounted transducer. Radar would be a little harder since the mounted angle of the transmitter/receiver is critical to proper performance. I think and reasonable person with some mechanical talet can do the job. Things get a little more difficult when installing a thru-hull transducer.
This stuff ain't that hard if you just do some planning and measure carefully.