Get a keypad deadbolt. Be sure and get a good quality one ("Schlage" - however you spell that - are good). The KwikSet ones are allegedly junk. Little cheap motors that drive cheap plastic gears to move the deadbolt. The deadbolt material itself is fine, the internal mechanism is not. Get one where the deadbolt is made "live" by the correct entry code, but you still have to manually turn a knob to move the deadbolt after entering the code. These are much stronger and better locks. It goes without saying that you want one with a key bypass, but I think they all come with this feature (your battery will eventually die on you, locking you out without a key bypass). I think these locks (the good ones) run between $100 and $150.