Replacement lids for Weber with Thermometer

I am trying to get a lid with a thermometer for my basic Weber 22.5 grill for my smoking needs.  I am surprised that I cant find them on sale anywhere.  Questions are:  1.  Would the lid from the 22.5 inch Weber Performer work on the 22.5 Weber Silver, and 2.  How the heck can you get one.  I am tempted to go to the Sunset Fair in Menlo Park next week just to see if I can snag one.  Right now am using the potato and temp probe approach.  My St. Louis ribs come out grate, but want to move on to pulled pork more now, and want the convenience

thanks in advance 

Ray