The problem I have encountered using medium bark for finer rooted plants is when it's time to repot, it's extremely difficult to get the bark separated from the roots - I'm afraid I have done a fair amount of damage to roots
I have got some nice orchids in stores - Trader Joe's, nice Cyms (noid) at Costco, local hardware and nursery chains.
Shipping costs are prohibitive to me, so it's local stores, or orchid shows/events (which is the best way to go!)
Vandas can be quite big and need a lot of light - not all, but many. Also love humidity. Can be grown in a pot or vase however.