|Compare the cost of doing it yourself with what you're paying now with your current contractor.|
What you're getting with your contractor will vary a little depending on the contract you signed but it should include:
1) If you do it yourself, then you have to purchase and maintain the equipment. That means having at least one spare wireless device handy for when one fails as well as what you need to provide adequate coverage. The way things stand now, that's up to the contractor, or should be. If you're seriously considering doing it yourself you're going to need to spend some serious time comparing equipment capabilities, warranty and support before you even purchase any hardware.
2) How technical are you? Depending on what you buy, your equipment, and wireless LAN (WLAN) setup can be simple to complex. If you go with wifi equipment that doesn't require a controller it will be cheaper, but, I do believe we get what we pay for in this world and you will find yourself replacing hardware more often.
Setting up a SOHO router with wireless in your home doesn't make you a network guru and the better the equipment you buy, the more it will take to configure and maintain it properly. This means you'll have to know more than you do now so prepare to do some serious research, then some serious learning.
3) As things stand now, if something breaks, you contact your contractor and can then stop worrying about it. If you buy your own equipment, who's going to handle those 2 am calls from pissed off tenants complaining that their wireless isn't working? Who's going to cover for you when you take off for a day or two or three? What about vacations....are you planning on giving them up? What's your time worth? Who's going to pay you?
Thinking about hiring someone to handle the support? Might as well just leave your present situation intact. If you're going to pay someone to take care of #3, you might as well have them doing #'s 1 and 2 as well.
All in all, I think it's best you stick with what you have now unless you are very technically inclined, knowledgeable, and willing and able to be available for support 24/7. Support of any kind is usually pretty ungrateful. Nobody notices you when everything is working properly and you're doing your job well. Everybody notices when you screw up. Very few people will ever thank you and most will blame you for every little problem.
If I lived in, was the manager of, or the owner of a building likeyours, I would NOT touch this with a 10' pole and I'm a professional with 20+ years doing IT and the last 11 specializing in enterprise level networking. It's one thing to do this for a living at a place of work and another thing entirely to try to do it in what amounts to your home.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.