If you belong to an Orchid Society, shipping costs are cheaper when doing an order with others. I have done this.
I order both orchids and exotic tropical plants and the shipping is expensive. Here are some orchid vendors that I have found to be honest and that always send me healthy orchids:
Hausermann's--I have been ordering from them for many years. The cost of their plants is reasonable but always check to make certain that it says that they are blooming size. I often get orchids in bud that are not said to be in bud or said to be a year from blooming. The roots on their orchids are usually amazing.
Al's Orchid Greenhouse (he takes the box to the post office and has it weighed so you pay for shipping what it actually costs. He also treats all his orchids as if they are a part of his private collection and, to be honest, he is very, very nice.)
Gold Country Orchids: Plants were a little younger/smaller than expected but they were also very vigorous and healthy. Shipping is super expensive, though, so definitely go in with someone else if you order.
Andy's Orchids is around $16 to $21 for shipping but, again, they are good orchids and are honest. If you ever have a question about how to grow the orchid, you can email him and he will call you and answer all your questions.
Exotic Orchids of Maui--very good, healthy orchids. They have a minimum order amount of $100 and it is thirty for shipping. I usually go in with other people when I order from there.
Carmelas--they often have really good deals, sometimes with free shipping. I have bought some very good orchids from them. If you do pay shipping, though, it is a flat rate of $30
Sunset Valley Orchids--I have always gotten very nice orchids from them but most of their orchids are not clones so the result can often be a surprise. They are honest and always send healthy orchids. I have always gone in with group orders so I am not quite certain of the order details.
Ecuagenera--if they come to an orchid show near you, pre-ordering orchids is the way to go! They are good and honest but they must bring the orchids into the US bare root which means that the orchids sometimes need a good dose of TLC. I have done group orders with others in my OS and been happy with the orchids that were shipped. This has not always been the case for others, however.
I hope this gives you a starting point.