I've got a wireless ADT system. My insurance company had a promotion WAY back when my wife and I moved into our first house, so the whole thing installed was under $200. She didn't like the idea of being alone when I was gone, and the alarm made her feel better. Being wireless, there were no wires to install, just the transmitters on each openning. The boxes are a little bulky on the doors, but after a month you honestly don't see them anymore. We liked the system so much, when we moved we had another installed at our new house.
Monitoring is not the cheapest, but it is basically offset by the insurance premium reduction. In order to qualify for the reduction you have to have FIRE monitoring, so at least one monitored smoke detector and a 'rate of rise' heat detector.
The monitoring does work, because my In-laws got a visit from the Sheriff one afternoon they came to feed my dog while I was on vacation. Also, as the batteries get weak in the transmitters, you will get a phone call from ADT telling you that you need to change them. The lithiums last about 4-5 years, and cost $6 a piece in bulk.
If you have a big dog, DO NOT get a motion detector... good way to get false alarms. Depending on your locality, you get 1 free false alarm, then you pay a fine for the rest.
Now, if your shop is in your garage, and you have automatic door openers, then you can't really have an alarm on the big door. One of the best ways to help secure the garage is make sure that folks can't really see what's inside. If it has window panels down at eye level, hang some thin curtains to obscure what's inside. Or, when you replace your garage door in the future, put the window panels up above eye level. When I leave on vacation I put a deep bale padlock thru the track, and disconnect the door openner.
I hear rush advertise a 'lasershield' alarm system, that is supposedly do it yourself, it's available at Best Buy.