The best way to make the lenses is to sculpt the frames, or to get them from someone who already has. Use some clear vinyl for the lense area, do a little bit of black airbrushing on the outside edges that will but up to the frames. Get some silver screen mesh, I suggest going to a target or wal-mart and heading to the cooking area. Find sifters and get a few of those. Cut the eye shaped mesh out of those and put them in behind the clear vinyl, glue it all together and your good to go.
I don't think it was ever easy to find accurate lenses. The frames, maybe. TDR has a good point about making the lenses yourself. Post something in the prop thread about the frames. I know there a bunch of people that don't read this part of the forum at all. One thing though, the originals had mesh fabric in the lenses, not metal screen. It's like those halloween masks you can buy with the black fabric that lets you see out but no one can see in, except in this case it's white.