Best online store for mini's?

[Lalato]

It was my understanding the molds to produce plastic miniatures were much more expensive, which is why there are relatively few companies making them, as compared to the large number of even small outfits making metal miniatures.

I think you're confusing something there. Plastic Minis have a higher up front cost. As you note, the molds can be quite expensive. However, if you're producing millions of minis (like WotC), the cost per mini goes way down compared to metal. The end result is that consumers can generally expect to pay less for plastic.

--sam