From what I recall, one of the advantages to their higher quality guns is the lack of mim. For example the PM series has few, if any, mim parts. While the CM series has mim, or maybe just more mim....
I'd be interested to know what model your part came off of. I have never had any parts break on any of my KAHR's but I do only have the PM series guns.
For the record, I don't mind paying for a broken part on a product that is out of warranty, especially if I didn't pony up for higher quality model.