How safe are cheap electronic deadbolts?

I have a shop that is away from my house, so I can't always be there. There are a lot of doors there, and I have to carry a lot of keys, so I want to replace a bunch of deadbolts with electronic deadbolts like this one: Gatehouse Electronic Deadbolt w Keypad 612773 Keyless Access Satin Nickel | eBay (http://www.ebay.com/itm/111654039613?_trksid=p2055119) I would like to spend more money on a higher end model but I need to buy several so that isn't going to happen. I was thinking maybe I could fill the key hole with epoxy, that way nobody could pick or bump the lock. Would that work? Are there any other ways for somebody to defeat a cheap deadbolt like that if it has no key hole? Since there is more than one door to the building, I'm not worried about the batteries dying. If one stops working I can still get in somewhere else.