they're super cheap i think... (you are talking about one of the knobs for the power seat controls, back or bottom, right)
if so, then check at your local dealer (just have your VIN handy)
the amount of the discount i could get you would be more than the shipping charges
but if it's something else, or it's more than $20 at your local dealers let me know
... and how the heck are there 60 views on this already??
(not directing that at you Fast, unless all the views are you)
but damn that's a lot of views.... maybe search crawlers or something)
I decided to go the super glue route and I will see how long that holds up. No sense replace a working switch just because one of the posts broke. I may still replace the buttons and the cover down the road. After taking it apart it doesn't look like your illustration, number 50 on mine has a 4 way circular switch that has "auto" marked on the top. There are also two number 51's on each side of the bracket that hold the switch. I know the circular button is by itself and separate from the switch but the cutout wasn't on the #50 cover.