I wouldn't buy an alarm from Quinn if I needed to...just some bad dealings with them over the years. I too would stick to Auto Temp, Audio Concepts, The Car Salon, or any other shop that has MECP (Mopbile Electronics Certification Program) qualified installers. I know that Visions, and all the shops I listed, installers are all certified, and if you're ever in doubt...ask. If they are, they have to be able to prove it.
I have an Auto Start two way alarm/starter, but I installed it myself. I've done this kind of stuff for quite a while, but I'm not doing much of it anymore on the side like I used to. Be sure that you're comfortable with whomever you decide to go with, don't just settle for the cheapest sale price. If your vehicle has a PATS system (or other style of stock vehicle security system), it may need to have an interface module installed so that the new starter/alarm can control the stock system.
Be advised, when you see that "installation is included" in the price of anything, this is a basic hookup and doesn't necessarily include things like door locks, interior lighting, or any needed relays or other accessories. Be sure to find out exactly what is needed before you agree to the purchase.