Awright, you get one Free Google.
Not a plug for a make or model (I don't have one and don't know of but one user around here.), but High Noon lists holsters for the S&W 457.
If you want a different style or real leather, look at their other stuff.
By the way, what holster do you carry it in for real? If it is a strong side straight draw holster, it would probably be ok for IDPA and better practice.
Of course if it is a shoulder rig or crossdraw or some such, you would not be able to use it.