I have been looking at one of those biometric locks that require a key to lock the door but a fingerprint to unlock the door. Cost is $200 though. Can hold up to 50 fingerprints and you can program what time of day the fingerprint can open the door.
In my experience, biometric locks are not quite ready for the mass market.
1. You hit the first one...too expensive, yet the prices are continually getting more affordable.
2. Offshore manufacturers selling direct to consumers or online retailers mean the products are more difficult to support. No one stocks parts, you'll have to remove and ship the lock somewhere even for a warranty claim.
3. Average consumer cannot grasp install and operating instructions. They are not only more involved than a simple door installation, the translation of directions to English is sadly hilarious.
4. Electronic locks, not designed for commercial use, still very prone to some failure. The electronics could become faulty, causing the bolt retracting motor to fail, the batteries to prematurely drain, the the print reader to malfunction, the processor to fail, etc. Want it fixed? See #2.
I have seen many of these products come to market, mostly from Korean mfgrs. This market is still in a 'shake-out' stage where brands come and go 'til a few will rise, like cream, to the top. Then the better ones would be the ones to choose from. There just isn't a decent track record surfacing yet.