Surety do it yourself Security equipment
There are web sites you can go to and purchase security equipment and install it yourself. One of those sites is www.suretydiy.com 
I installed my own security system and it took me about 8 hours or all day long to read the book and do the programming and install all the sensors and such. If you are mechanically inclined it may take you less time.
Ask yourself what your time is worth and then it would be prudent to get proposals from licensed, trained security companies and use a UL listed Monitoring station.
For this example I have included the following equipment that was priced off the above web site :
2GIG PIR Motion $51.65 each (2) = $103.30 2GIG Panel with touch screen $268.50 3 Door window contacts $23.50 each or $70.50 Yale Touchscreen Z Wave Key Free deadbolt $226.95 LiftMaster MyQ Control panel for garage door $46.95
Total off the site was $716.20
This site is a great resource for security equipment although you can check all of your options to make sure you are getting a quality install done by licensed professionals and monitored by licensed professionals.
Using the same part numbers and signing a 3 year contract through Peak Alarm you can have this system installed for under $500 dollars. Research the monitoring well because some of the monitoring stations are not UL listed and some do not offer the remote apps that you need to control your locks, lights, thermostats and security system. When getting the locks you end up having to pay another monthly fee and when getting the garage door opener the same applies and there is an additional charge for the camera. Many sites will quote you a monthly monitoring fee but not include the cellular plan which we are $10 per month for but many companies charge over $20 for per month. If you want Elite control or smart phone control it is $15 per month for the cellular and elite plan.
The 2GIG is a great panel and can have many different options added to it to control lighting, thermostats, locks and much more.
www.peakalarm.com Larry@PeakAlarm.com 801 428 1384
Peak Alarm has been in business for over 45 years Peak Alarm is insured, licensed and has an A+ rating with the Better Business Bureau. Peak Alarm has 5 offices in Idaho and Utah Peak Alarm has the ability to do any size installation Peak Alarm can subsidize a portion or all of the installation and equipment on your security system Peak Alarm can do a 60 month, 48 month, 36 month, 24 month or 12 month contract depending on your needs Peak Alarm can even do a month to month contract but we could not subsidize the installation or equipment in that case.