We old 'uns who prefer to spend our money on flying rather than poncy Raybans - prefer $15 clip-on - or the more fancy flip up ones for $20 (they sit nicely flush with under the peak of a baseball cap (very useful to block the sun) - out here in the sunny tropics sunglasses are a must but not all the time. OK they can look a bit silly for the younger - Sky Captain opf the future but, just take them off when you're walking on the ramp!
One other thing to bear in mind is that if you "need" sunglasses i.e. you find it impossible to fly in some conditions without them then you will need two pairs as you should have spares available and readily to hand - plus a spare of your clear glasses - the cost adds up.