You might just need to bump your entire question once a week or so. I don't recall any recommendations for local singapore purchasing.. but you're certainly close to japan so the shipping rates for japanese manga can't be that bad if you bundle up your orders into one shipment (assuming you can read japanese).
I use a combination of
www.amazon.co.jp and nippon-export.com for my JP manga purchases (I live in the US). For Region 2 anime&music, I tend to use cdjapan.co.jp and couple of others.