The three types I have, about $45 for leather, $20 for nylon:
Nice leather thumb break Ruger holster made by Triple K. A smaller version of the Ruger/Triple K Single-Six holster. They have went up $4 recently!!
http://shopruger.com/Bearcat-Holster-4-barrel/productinfo/84188/
Hunter's 1100-46 leather Snap-Off belt holster, the classic Hunter design with an over the trigger guard strap. They also make Frontier and Double-Loop western styles for it, which I don't have.
http://www.huntercompany.com/index.html
Edit, 7-24: The following two nylon holsters swallow a Bearcat, up to the end of the hammer spur and the back of the trigger guard, but they are a good fit otherwise. Good for range use or wet weather:
Blackhawk has a nylon hip holster with an over the hammer strap, Size 12.
http://www.blackhawk.com/product/Hip-Holster,958,137.htm
Uncle Mike's has a nearly identical nylon holster, but I like the Blackhawk belt loop better. Their size number is 7.
http://www.unclemikes.com/products/sidekick_hip_holsters.html
Ruger's is through their website, and I'm pretty sure Midway carries the others.
This is all the ready made Bearcat holsters I know of. Everything else is order, wait, and spend twice as much (or more).