I second Mike on joining an orchid society if there's one nearby. Last November, I joined my county's orchid society. Since then, I've acquired free orchids from a donation from a nursery and won orchids from raffles. Membership fee is $15 per year! Plus, as a member, you can learn from other members who have been growing orchids for years.
The following growers that have online "nurseries" have quality orchids (and I've ordered from them and will again
):
Aloha Orchids Exotic Orchids of Maui Andy's Orchids Tropical Orchid Farm
I've heard good things about the following growers:
Santa Barbara Orchid Estate Norman's Orchids