Replacement lens for Better Beamer?

Has anyone here ever had to replace the plastic fresnel on the front of a flash extender? Mine's torn from snagging on so many trees, hoping to buy a few because I have a bad habit of beating equipment up.

I did buy a small package of "reading magnifiers" (thin fresnels) off of ebay, but the grooves on the material did not focus the flash enough to be helpful. I know replacement lenses can be bought from B&H online, but I'm trying to avoid paying $10/lens when the uninflated costs is probably $.50/lens for a flimsy piece of plastic.

Any suggestions on where to buy the correct fresnel, or any guesses to correct specs on the material needed?

Thanks,
Dave

About 3 years ago I saw the same exact fresnel lens in Barnes & Noble bookstore. If I remember correctly it was cheap too, about $3.

kosin wrote in post #9447924
About 3 years ago I saw the same exact fresnel lens in Barnes & Noble bookstore. If I remember correctly it was cheap too, about $3.

Thanks Greg, that's a start. Unfortunately, I order a replacement that appeared identical on ebay in '09, but the grooves and thickness were just a bit different. Consequently it didn't carry the light whatsoever. Must be trial and error in getting the right part, as specs aren't given by manufacturer.

If anyone can come up with a replacement model number, that'd be great.