Unfortunately the slider pins aren't available as separate parts. Bummer! As you say your bent pin is part of the more expensive (like �300) piston side, if it was the smaller one it's part of the bracket which is a lot cheaper.
Shame also that it's the right caliper as that unique to the XTZ, making finding a secondhand one harder! Unless you find a nice helpful person comes along, who has upgraded to a WP front end, and has only used their left hand caliper... Uberthumper, JMo etc.