I ordered from Maryott's this fall and was MORE than pleased. I am near Jack/Mark Carpenter's in Texas - they have gorgeous things - am sure they would be super at mail order. Lots of other good ones too....am sure others will chime in.
Judith

Try the lily auction.

Would the "very floriferous gold one" be STELLA D'ORO? If so, you can usually find it at any garden center (including Lowe's or Home Depot). Online stores like American Meadows generally have pretty good bulk deals on it as well.

For newer, more expensive varieties, the options listed above are a good start.

Nate