Here is an older but simular thread:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/155738-has-any...ml#post1618012
And a copy of my reply in that thread that answered how much I paid CRIS for 16-50mm SDM motor replacement:
8/17/2011
"My DA*16-50 is currently at CRIS for SDM replacement.
The repair bill = $195 [includes return shipping & 6 mo. warranty]
The SDM motor is being replaced. Which makes sense, since CRIS is going to warranty it for 6 months.
I sent the lens in on July 12th, so it has been gone just over 4 weeks so far.
I got the repair invoice on July 25. The CRIS repair includes a 6 month service warranty.
update 8/18: CRIS just charged my CC, so that means the repair is finished and the lens is on it's way home.
update 8/19: The lens arrived last night. It performs just like new. Auto-Focus is performing flawlessly again. Cudos CRIS!"