Check out Van Engelen's Bulbs. They are the wholesale side of John Scheepers. I've ordered from them and been happy.

I've also been pleased with Brent and Becky's bulbs especially for lilies. Like most bulb sellers, they set pricing so that the more you buy, the cheaper it is per bulb.

These two companies are the two I regularly look at for bulbs after trying several others. I don't know what you consider good bulk pricing, but my experience with bulbs is that often you get what you pay for as far as quality. Less expensive bulbs are often smaller in size which in turn affects the number and size of blooms. Or sometimes they are the really common ones such as plain yellow trumpet daffs and plain red tulips. Or if you are really unlucky they aren't healthy, though I have only rarely run across that.