About 10000 HKD now. I forget the exact amount (and several sizes are available, an obvious marketing ploy by Remy to obfuscate the price). Nowhere is it under USD 1000 per bottle (except for counterfeits, which are plentiful, and then you are getting XO in a nice bottle -- I suspect many bars serve counterfeit Louis XIII). The stopper is slightly different on counterfeits from the genuine, that is the easiest way to tell without tasting.
I have seen it in a 50ml size on the web for USD 180. No idea how genuine it is or how nice the miniature bottle would be (the empty bottles sell for several hundred dollars). I've never dealt with this store but they have interesting stock http://www.drinksite.com/product.php?prod_id=1062