Door locks

My original post is here: viewtopic.php?f=2&t=18697 I will be installing two solid MDF doors with an air lock between for my studio. I am trying to figure out what closing and locking hardware would be best. From what I understand automatic door closers and a handle where I don't have to drill into the door is ideal but, what about locking the door. What is the best way for me to lock the door? I have looked around. Google shows me locking devices where I do have to drill into the door. Others have mentioned a deadbolt. What do you use to lock your sound isolation doors? What would work best for me?

I have just been researching sort of the same thing. I am about to settle on the Lockey M210, it's a mechanical keyless deadbolt, it looks like it requires drilling small holes through the door but not the big 2 1/8 standard hole which helps. And it is available with an extension kit for doors up to 5" thick, with which it's about 120 bucks.