We went with a wireless system bought online that if entirely wifi based. We bought an LCD touchscreen for the front door and hid the master unit. We had to pay for the equipment up front but have no contract and it amounts to roughly the same if not cheaper than an ADT type of solution. I installed all the contacts for doors and windows. The wireless ones can be monitored for 8 bucks a month or more, are expandable on you dime and time and so far have been great. You can also self monitor – have he system call multiple phone numbers if an alarm is triggered.
We have a massive dog and I bought signs off ebay a year ago but dear wife wasnt sold so i bought the system. I shipped both the signs and the system to work so noone knew where I was installing.