In the US and Canada, Digi-Key, as far as I can tell, is up to snuff.
I know you're looking for online sites, but I think it's worth mentioning : surplus stores are your friends! I visit 2 regularly, and I always find something interesting, at ridiculous prices.
Today I found right-angle PCB mount LEDs, some yellow and some green, at 15 cents a piece. 15 canadian cents at that! I also got some 3.75" x 12" chinese Veroboard knockoffs for $3.50 each. The real deal sells for $28 before taxes around here!... They also have a bunch of fixed and variable voltage wall warts for ridiculous prices.
Their customer service sucks, the store smells, but surplus stores often have by far the best prices.