The worst thing you can do in this situation is try to do it on the cheap. 

Just because something is cheap doesn't make it a good investment, the opposite is also true.

The best tenants were in my condo's that were not as cheap as house apt's. 

I understand the advantages of the technology and processes plus in some areas land being cheap. 

I've done it before with no problem with an attached older home that I got cheap, cheap, cheap.

That is cheap and as John says a liability issue.

As far as the locks being changed you can pick up a cheap lock pick "gun" on Amazon for around $40.  

"Unique" items, or something that the average person knows little about can sometimes be boght cheap enough to resell on ebay (I have another friend who does this with sewing machines).I was at a HUD live auction and saw a couple of houses sell at auction for 10% more than the they could have been bought off the MLS that afternoon.

The devices that do the monitoring are relatively cheap and many are wireless.Has anyone implemented anything like this in their rentals?

I think a key factor missing here is the type of person this program may or may not be good for.For me as an investor, I look at my home mortgage as a great tax deduction against my income and very cheap money to borrow.