[Buying]  I Need Mercury Anubis Brave Version for the Best Price

I think that not a lot of people have it here. You should try going on Yahoo! Japan Auctions, the best prices are probably there.
You need to use a middleman service like OkinawamTS, Mail Order Japan, and RiderProxy, who live in Japan and who will send you the items once they get them. You can trust them.
Or you can try on eBay. It's not much more than the normal version on there and the price is the cheapest you'll find outside of YJA.