Hi Malc,
i had a quick look and found it very hard to find a good pair in the UK or a good priced metal frame pair anywhere in the world - i would never ever be able to justify $400 on a pair of sunglasses.
Anyway here what i have found
All ebay items tho
170338201837 you can find these ones quite easily but i think these are cheapest i have found - i have a pair of the brown lense ones and i find them pretty good for the money.
380131779250 same ones but in the UK
400056140230 again official EP merchandise and look OK for the money
180369255163 have managed to find these in West Sussex and they are listed as being metal chrome frame but i would message and check to make sure
120434021690 also have found these but again id check to make sure the frames are metal
320384713557 or try these for a real pro look
sorry cant be of more help Malc
oh and well done on getting the Best Scottish Elvis havent had change to say congrats yet
Cheers
Joseph