you can check sgcollect.com for a listing of the shops. I'm not 100% certain, but most shops do not ship overseas and if they do, they will charge 'market' prices (ie: what the item is going for online or on eBay), which defeats the purpose. Bargain prices can only be got when you're physically there to buy and pick up from them. It's much the same for HK toysellers.

I think that is mostly the case but I could be inaccurate and correct me if I am.