I bought several pairs over time a few years ago from Zenni's - bifocals, sunglasses, and both. Never had a problem. I recommend them.
Now I don't need prescription glasses, however. Had cataract surgery (both eyes) and the doc installed new lenses that gave me near 20/20. Still need +1.25 readers because I nor insurance would spring for the extra cost for bifocal lens replacements. (Which the doc said were a bit difficult to get used to anyway.) I buy the readers and sunglasses off the shelf for a few bucks at Wal-Mart and they work fine for me!
1999 CB-750 Nighthawk
1988 GL-1500 (gone but not forgotten)
1975 CB-400F (long gone but fondly remembered)
1970ish Kawasaki 90 (just plain long gone)
1965 Cushman Super Eagle (long gone and thankfully forgotten)
1957 Sears MoPed (long gone, but some good 'first bike' memories)
K 4 D I T