Well, worse comes to worse, you can just log on to
RangerJoes.com and buy the Military Angle Head Flashlight for $8.50. Just click on the Online Catalog and scroll to the Flashlight section. It comes with THREE different filters and one spare bulb. All made in the U.S.A.
I've ordered from Ranger Joe's plenty of times. They're in Georgia - shipping is very reasonable.
[*] Edit: almost forgot to mention
Flashlightlens.com - give them an email and see if they can custom make you a replacement lens/filter. They're quick to answer emails, too.
-Jim