You'd be surprised at the amount of training required for an autotech at bestbuy. When I first started doing it a few years ago I spent almost 3 months with a master certified tech who had nearly 15yrs experience before I was allowed to do much more than sit in a vehicle and observe. Thered also the MECP exams that are required to pass and keep your job. They're the equivalent to an SAT in length. Couple hundred questions. I assure you if they also aren't minimum wage hacks, more like triple what you're thinking. I've known a few techs making over 60k.
As far as install go there are typically very few "interrupts" where an installer would physically cut a wire, 98% of the time it's either a military splice or military splice and solder if it's a data connection which anymore is about 1/3 of the wiring w the keyless entry systems and CAN/OBD interface that's needed on modern vehicles. The only interrupts I've really ever done are for parking light control when called for (typically by honda and toyota) which realistically aren't "required" technically but are used to know the vehicle is running and to obtain diagnostic codes for troubleshoot and programming. The exception would be if you did insecurity add on that has a starter interrupt feature. That's pretty well impossible unless you interrupt the starter wire.
The basic remotes that compustar and viper offer on the DC3 and DS4 systems are very small, smaller that the head of your key. Half the time a t harness is involved anymore which usually handles the ignition and obd connections vastly limiting the amount of wire to wire connections that need to be made, ironically though I've seen several bad harnesses that are pinned incorrectly, loose, faulty connectors, etc, far more than I have an installer actually doing the job incorrectly.
Cost wise expect 3-350 installed unless you catch a sale. I'm going to do my own here next week most likely and can snap some pics showing the process. I have an 03 so it wont be the exact application but same idea...yours would actually be less involved because the t harness does more in terms of connectivity on the 3v vehicles since they are heavily invested in CAN control.