I have purchased quite a few plants (don't tell the fiance') from Andy's and I *LOVE* them. I haven't been disappointed in any of them.
Andy's is in a tie with my other favorite site:
Exotic Orchids of Maui.
Andy's has a larger ongoing selection but keep a eye on EOOM's site, they release new stock constantly. I've purchased beautiful vandas, bulbos, dendros (mini's), Dendrochilum, epi's, and Masdevallias from both of them and have never, never been disappointed.
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They are a bit more pricey but worth it!
Oh, as mentioned, be very very careful with some of the e-bay sellers. As mentioned, "rare" is a very loose term on e-bay and can mean anything from a new cross, something harvested oversees (illegally), to "rarer than a dandelion"
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Check it out carefully. There are a few sellers on there I really like but some I've come across are horrible!