I would say there's two very important factors to look for in a learning lock, which are conducive to a very productive and satisfying learning experience:
- consistently repeatable outcomes: practice lock should have outstanding manufacturing tolerances
- ability to control difficultly factors in a granular way: for locks, this means being able to change the pins; the quantity, type (normal, spool, mushroom), and even the position of the pins change the difficulty.
With that in mind, I would highly, highly recommend, Mr Wizard's ultimate challenge lock. It in incredible, cheap, and will take you from the very beginning (just put in one pin), to the advanced (put in 7 security pins).
Problem with getting a easy cheap lock is, well, turns out lockpicking is so easy that, most people can learn how to pick a padlock within 30 minutes. After a couple hours of picking the same lock and getting faster and faster, the lock is no longer a challenge at all, so it becomes boring, and you just want to chuck it aside and move onto the next level. So effectively you've invested let's say, $15 in a lock that you only got a couple hours worth. Vs, for $50, Mr Wizard's challenge lock will last way longer than that; I'm *STILL* finding it fun even after picking it for hundreds of hours!
