$700 huh? Shoot me a PM.
I have been sort of shopping for one since I bought my Prelude two years ago. I can say in the past 2 years there appears to be a significant drop in interest. There will always be the mugen collector, and no doubt about it, it is a rare item. But still, our 4th gens get older and older as everyday passes. Even that guy Aries sold his Prelude. I've had pictures saved of that thing since I started shopping for one of these cars. It will always be expensive for one of these bumpers... usually not much over 1K on the bay. Of which I have only seen 3 in 2 years. The main thing keeping the price up is the fact that there are no replicas available here in the States.
Still, it sort of feels like Prelude interest is fading as time passes, mugen parts or not. But the good news is there will always be forums like this, with new members continually registering. Hopefully the numbers will increase. I know I plan on being here a long time.
EDIT: just some spelling.
Oh and don't spend more than $1300, especially if those lenses are frosted. Polish can work miracles, but thats still time or money for you.
2nd EDIT:
Just noticed you are in the UK. I'd say maybe try to pay a little less. Aren't the replicas available here:
RRD STYLING -- Prelude Corner :: Fotopic.Net