On where instead of the grill? - In the brake ducts? Cut into the Grill?
Mounted in the brake ducts, they're probably from a Sunny GTi.
In the grill is a custom job I think; I've seen it before, but didn't really like the look. I'd be tempted to put them behind it for the aesthetics, and accept the honeycomb pattern you'd get as a result.
instead of the front grill?
i know someone who has a setaverage £400 rare