I just got that pistol in June and I love it. As for the holster, I'm using the Blackhawk size 1, $20 at Academy sports. Uncle Mike's is recommend too, size 1. They don't clip on, belt slides through.
Ruger's website, if you haven't already looked, has recommended holsters listed. At home page, click the customer service link at top of page, then click holster compatibility chart.
It would be awesome if someone made a Serpa holster, but since it's not really considered a defensive or service weapon, I guess that won't happen.