I've ordered a plant from each of the following eBay vendors in the past couple of months and here's what I have to say about them:
elvis.813 - She operates a flasking service and I bought a flask of Cattleya seedlings from her. She was very communicative with me throughout the whole transaction and even waited 3 weeks (at my request) for the weather to warm up before shipping. The seedlings arrived in excellent condition. I would order from her again without hesitation.
cowboyflowerman - his prices are so low it seems too good to be true. I ordered an oncidium from him which arrived with some very cramped roots and very shriveled pseudobulbs. Still, the plant was bug free and with two new growths, now growing a third. A quick repot and a couple weeks later, and the plant is fine. I would probably order from him again if price was the priority.
mbufalo12 - Ordered an oncidium. Seller contacted me after the sale to know if I would wait a couple of days on shipping so that time in transit could be minimized. Nice-looking plant with plump pbulbs arrived in bud, wrapped in newspaper. All the buds opened up a couple of weeks later and the plant is looking good and sprouting a new growth.
insituorchids - Sent me a very well-packed, gorgeous, mounted Bulbophyllum medusae (I later unmounted it). Not a single blemish on any leaf and the plant with four new growths well underway. Correspondence was excellent and he took time to highlight care for the plant. Recommended.