I got a pair for out on my bike as I was really concerned about getting dust/flies etc. in my eye.
Ended up getting a pair from
http://www.wiggle.co.uk,
I got the dhb Triple Lens glasses, they're still on offer at £19.99
Out of the 3, I like the blue lens as the tint is stronger at the top and fades down, so it blocks out the glare from the sun but still lets you see the ground. I find this better than even tinted glasses as sometimes they can actually make it harder to see.
For my hols I got some polarised glasses from Next for about £15 which are good because they are not very dark but still really filter out the glare.
They also had photochromic sunglasses for about £20 which vary in tint depending on how bright the light is. I thought you could only get this feature in expensive prescription glasses like in the adverts, so this is a good solution for contact lens wearers.
When are we gonna get photochromic contacts?!
I hardly took my sunglasses off on holiday and when I got back because I found the bright light particularly uncomfortable - turns out that was down to 3 broken stitches! Went the hospital only last week and the sun is no problem now. Can't believe the difference it has made!
Rob.