I've got a couple different kinds of stars. One has a red Cree, one has an old Luxeon, another has something I'm not even really sure what it is. I just know they're all 20mm stars.
I used to have an old light... ALX-1113A, I think. It used a full sized star. Swapping it out was just a matter of loosening one Phillips head screw (used to hold down the star) and soldering two wires. Something like that would be ideal. Under $20 would be nice. Orange peel reflector is a definite bonus. Anything that requires 3xAAA in a carrier is a negative, unless I can bore out the tailcap and stuff a single 18650 in there instead.
The Romisen RC-G2 would be my ideal choice, but you can't fit a 20mm star in there. I'm not going to turn down the stars I have, nor will I take the emitters off them.