From wiki,Pretty sure you can get a 10/22 magnum too.
It was manufactured for 9 years till 2006 and only about 50,000 units sold. Compare this to over 5,000,000 sold of the 22 LR version. Then there is the other assumed answer that the 22WMR was discontinued due to extraction issues and breaking bolts.
gun broker had one listed for over $1000