I have a Ciener 22lr conversion and love it. I bought it directly from Ciener: http://www.22lrconversions.com/
From memory it was $199 for the kit and another $35 for the second magazine plus $10 shipping.
The kit shoots very nicely and is accurate. Some people have complained about it because it has fixed sights, no safety, and doesn't hold the slide open on an empty magazine. These cons have not bothered me at all and I find I enjoy my time at the range even more. I can shoot all afternoon on a pittance.
[edited to add] It has eaten everything I have fed it. My wife has a new Sig Mosquito which is proving very particular so I get all the ammo the Sig won't eat. So far I have about 700 rounds through it and not one problem.
I understand (but am not sure) the factory 22lr conversion addresses the cons I have stated above. It also costs about $100 more.
Like I stated above I bought mine directly from Ciener and this is the worst part. You have to print out the order form from their website and then mail it and your money to them. You are now in the dark. There is no contact with them on their website or by phone. I have read that other people prefer to buy these conversions from places like Brownells.
I consider my conversion kit money well spent and would buy another.
I hope this helps