Most suppressors I've seen for a .22 range from about $250-$600. Liberty makes a titanium for about $600. I been over to see David and have used the titanium on my 15-22. He's really a great guy.
If you guys want to see and hear a suppressed 15-22 (as well as some others and full auto) check out this video on Liberty's web site.
Liberty Suppressors - Essence Premier Rimfire Suppressor