While I am not sure about The Dude and his sunglasses. Walter is definitely wearing military issue aviators.
In the second to last Bowling scene, you can tell when Walter takes off his glasses and the ear piece is very curled. Tell tale sign that they are not designer.
The sunglasses that "His Dudeness" is wearing are Ray-Ban's, however they are not the traditional ones that everyone wears.
The Dude is wearing a Vuarnet 003 frame but I'm not sure about the lenses. Back in the 80's, lots of makers were using the same Vuarnet frames including Ray Ban with their Cats line. Ray Bans or not, those are a Vuarnet frame. Perhaps the coolest tribute to the dudester would be Suncloud scr pink lenses in this frame. Suncloud did make them but expect to pay on eBay.
Walter has Ray Ban Kalichrome shooters, the same ones that Hunter wore in Fear and Loathing and the same ones that Phil Spector wore in Easy Rider.
I once sold the same glasses the Jean-Paul Belmondo wore in Breathless and the same LA Eyeworks that Tom Cruise wore in Rainman on eBay so I have an eye for this sort of thing. The Big Lebowski wears Vuarnets. Take it to the bank.
Which pair there were several...
Otomix...I have a pair for my Lebowski costume.
The Big Lebowski is Tony Hawks favorite movie
The Big Lebowski... he had "Bunny Lebowski" and a "Nihilist" floating in his pool.
The Big Lebowski was released in 1998.
Maude Lebowski (Julianne Moore) in Big Lebowski
The duration of The Big Lebowski is 1.98 hours.
The Big Lebowski was created on 1998-02-24.
The Production Budget for The Big Lebowski was $15,000,000.
The Big Lebwoski is a movie that was made in 1998. Jeffrey Lebowski (aka The Dude) is played by actor Jeff Bridges. The movie received generally positive reviews from critics and has an IMDB rating of 8.2/10.
Julianne Moore plays Maude Lebowski.
Aviator Style sunglasses with a yellow lens, used by pilots and for hunting/shooting