Been looking for one as well and the prices for an weapon light are absurd.
Sooooo. Today I picked up an Vikings Tactical polymer weapon mount and then went to Wal Mart and picked me up an Maglite LED XL50 light with 130 lumen. Fits perfectly after I removed the insert on the mount.
One hit for high. Two for dim. Three for strobe. Runs on 3 AAA batteries and I much prefer that over CR123's.
Will it hold up and work? Don't know. But this light is under $30, uses common batteries and isn't uber spendy. If it holds up I'll be happy because it isn't over bright and doesn't give me backwash reflection too badly.
This is my econo answer im going to try.
