You can pick up a Heritage Arms rough ridercombo 22 lr revolver new for around $140.00. Add a cheap nylon holster for another $10-15 . Even comes with the 22 mag cylinder.
I just picked up one for when working around the gun club, cutting grass etc....or fishing in some strip ponds.
A .22 for all purpose carry can come in several flavors: single action or double action. The S&W 317 is a very nice example of an ultra light double action. Mine weighs 14 oz. It has good sights and a very good trigger. I changed my 317 to a black serrated ramp front and conventional notch rear. Just a matter of personal preference. If you are willing to handle a little more weight, a S&W 63 would be good. They weigh in at 30 oz., but I find the extra weight helpful in good shooting. Another pound heavier are the S&W 17 and 617s.
In single action flavor, an ultra light gun is the Ruger Bearcat. The only problems with the Bearcat are very small grip and small, fixed sights. A little more weight is the Single Six. The SS has the full sized Ruger grip and good, adjustable sights. I have no experience with others. For those, you are on your own.