Another option might be the P-4. (http://www.ruger-firearms.com/hgpages/p4.html) It is a 22/45 instead of a Mark II, but you should be able to find one for about $200 (I think) and it has a 4" barrel and adjustable sights.
I have been thinking of picking up one of these myself. Whatever you decide, I am sure you will enjoy it.