First important point - cheap!
Second point - I've got large head, which does affect choices a bit...
At the moment I've got some DHB yellow glasses which I wear for most day-time rides but they're starting to get a bit scratched up and loose. And I've got some old clear safety glasses nicked from my last employer for night-riding.
I'd like to replace them both with a set with replacable yellow and clear lenses. I find its never bright enough in the UK to need dark lenses, especially if you're in and out of shade in woodland etc.
Any suggestions gratefuly received!