Some time ago I spotted an art supplies store "Artemedia" at Festival Citylink, Bandung. They sell some kinds of sketchbooks so I decided to buy one of the most expensive sketchbooks I've ever bought in my life, XL AQUARELLE from Canson.
The sketchbook costs Rp 102.000 (A4) and Rp 172.000 (A3). Each has 30 sheets of 140 lb paper, so it's thick enough to make watercolor drawings.
I love the texture of the paper and it's also nice for pencil & colored pencil drawings.
So, I love it. Even it's more expensive than my previous ones, it makes drawing more fun because I can try various art medium without damaging the paper.
Where to get it: http://www.artemedia-hidayat.com/seller.shtml