I use these cheap Milenco mirrors, the 3698. Paid £20.
http://milencolimited.vpweb.co.uk/Products.htmlThey are far more secure than the aeros i returned, and the grand aeros i still have for which i paid around £55.
The cheap MGI are made by Milenco, they use two straps, and two clamps with a safety lanyard.
I've used them now for two years, and only retain the Grands just incase i need a spare quickly.
Only thing to watch for is the positioning of the strap anchor nearest the door, if its too close it will touch the body work when the mirrors are folded, to eliminate that i have a marker on the mirror using black pvc tape, you don't see.
The MGI clamp screws are nylon, but i have had zero problems, and the mirrors came with a spare, i fully recommend them, i think the clamp only type are very poor in comparison to the previous ones i had that strapped on, but i couldn't use them on the CX-5 due to fouling the body if the mirrors are folded inadvertently.