Keypad entry for multi-unit apartment building

[Michael Seeker]

I recently purchased a 6-plex and am looking for a better approach than the janitors key ring or the valets keybox. I've been looking at the numeric keypads that allow multiple number combinations as a potential alternative (like this one: http://www.amazon.com/Schlage-FE575-PLY-505-Auto-Lock/dp/B00486U3WC/ref=sr_1_5?s=hi&ie=UTF8&qid=1328745898&sr=1-5)

I have a regular keyed entry for the main door, this one is almost a no-brainer as I don't want ex-tenants to have access to the common area after they move out and with 6 units, there could be a lot of rekeying.

I'm thinking of setting it up as follows:
Main door
-8 unique codes
-1 for each unit
-1 "master code" that only I have
-1 "maintenance code" that I can give out to contractors

Each apartment
-3 unique codes
-1 code matches tenants front door code
-1 code is my master (this is on all doors)
-1 code is maintenance code (also on all doors)

Without doing much shopping around, this would cost me about $700 up front, $100 per lock.

Here's my list of pros/cons...I'd love for somebody to add to it
Cons
-High up-front cost $100 per lock

Pros
-No lockouts
-No rekey fees
-No hassle for me to get in or give code to contractor
-NO KEYS

What do you think?