Re-considering my vendor for this year. I always buy in bulk for the best bulbs and prices, and can provide an EIN tax number if needed. Who are people using?
Wholesale / large quanitities
Ednie Flower Bulb
ADR bulbs
If you buy in bulk, I may purchase many of your left overs!
Have you tried Van Engelen? They are the wholesale arm of John Scheepers, and sell in large quantities. I have ordered from both, and they are very good.
http://davesgarden.com/products/gwd/c/44/#b
Here is their web site:
http://www.vanengelen.com/
I ordered a large number of bulbs from them just last year (probably my fifth order), received very large bulbs, and of the 70-80 I ordered, 100% bloomed. I was particularly pleased with the allium karataviense.
Netherland Bulb Company is an excellent source for bulbs, and they're slightly cheaper than VE.
The end of season sales from Van Engelen are also great, if you can wait that long.