I've had good results with daffodil bulbs from Lowes. Generally, I try to stick to the most premium bulbs that I can afford. I like buying bulk from local nurseries, as it is a lot easier to examine each bulb for size, firmness, and quality. I bought a bunch of bulbs years ago from Michigan Bulb Co, and while they were cheap, they were also very poor performers. Look for bulbs either from Holland or NW Washington State that are rated for size. If you buy online, try to get ones from companies that are actually growing the bulbs.

But honestly, I find good bulbs at the local Kroger/Fred Meyer store. Just make sure you take a close look at the bulbs to make sure they are not soft or rotting or hollow.