Not sure if this has been posted before, did search - but found nothing. Anyway, here's my Bijou Rush mini-guide.
You're looking at nine different bijous: All of different colours, all with a standard gross drop rate of 2% (1-3%). This typically means, you'll have an 18% chance to grab a bijou (One in Five).
Killing five mobs typically takes around 30 seconds in Zul'Gurub, assuring you're in fitting raid gear.
Each pack of mobs will on average drop one bijou if we look at the statistics, and this means that you'll typically be grinding up to 60-70g every 30 seconds to a minute, dependant on your server's market.
Approaching 4.0.3a, probably coming at the start of next week, the market is becoming very versatile and a very very good area to tackle on the auction house.
Grinding 2 bijou's, plus travel time will take around a minute and a half (1:30) - Going by these stats, we will be making 1200g (20 Bijous in ~15 minutes).
Per hour, this will fetch on average 5000g for around 70-80 Bijous.
A full day's farming will, in accordance to how hot the Bijou market on your server is, will fetch 50,000g for 10 hours farming.
GoGo get farming!
-Z