I have 3 FALs, and I love them, love shooting them. Having said that, though, unless you have a DSA or got lucky with a kit gun that shoots really well, spending $800 or more on a scope for it might be over kill. Also, unless you're hand loading, I'm assuming you're shooting milsurp ammo...so once again, inherent accuracy might not warrant high $$ on optics.
The Tri-Lux scopes are cool, relatively cheap (when compared to Acogs and Elcans), and preserve the original look of the FAL. I'm pretty sure I've seen a Tri-Lux for both inch and metric FALs, too.
I've used a Kobra red dot sight on one of mine from time to time...it looks a little funny, but it certainly works. The weaver mount ones go for about $135 these days. The Kobra is pretty rugged, much more so than the cheap red dots (BSA, etc). Check out the Kobra here:
[url]http://tantal.kalashnikov.guns.ru/bstkobra.html[/url]
Scroll down towards the bottom to see the weaver mount syle.
You'll be the only guy on your block with a Commie scope on a Brit gun lol.