Where can I find a motorcycle/car *MIRROR*? Just the mirror!?

I've accidentally broken one of my Honda CG125's mirrors by leaning the bike against a wall. The stand is intact, only the mirror is broken. I'm now looking for a round replacement mirror to snap it in the place of the old one, but I can't find anywhere just the mirror! Everywhere I looked I've only seen for sale the whole mirror system including the stand. I don;t need that and it seems wasteful to buy the stand when I don't need it. I even cut a round shape from a plain household mirror and glued it on the stand, but I then noticed that it's not convex as the old mirror was, so I'd rather replace it with a proper vehicle mirror or similar. The shape I need is: round with 10.5cm diameter, but even 10cm would do. I could even cut out this shape out of a larger vehicle mirror if I could find. Any idea where I could purchase such a mirror, JUST the mirror, not the stand? I live in the UK.