These are all good, reputable sellers I have used for many years. The only exception is Locus who I have only used once, but I have only heard good things about them so far. Other exception is Rakuten which is an online mall, no problems so far, but be aware that thousands of stores are represented.

fantofan.jp (Jap) - Toys and 3rd party exclusives
angolz.com (HK) - Toys
anime-export.com (Jap) - Toys
locushk.com (HK) - Toys
1999.co.jp/eng/ (Jap) - Toys
rakuten.com (Jap) - Online Mall
amazon.co.jp (Jap) - Books and discs (will not export toys/electronics directly)
hmv.co.jp - (Jap) - Books and discs