Claudia, I did think about that. But Priority Mail comes with automatic tracking and $50 insurance. They always ask if there is anything liquid, perishable, fragile, etc. and I'll say "fragile". I haven't tested it yet, but I'm pretty sure I can fit way more than 40 in the bubble mailer, and I may first pack them in the same lunch paper bags they are currently in. Even if a couple did get smashed, the receiver will probably still get a whole lot of bulbs. I considered the small flat rate box, but very few bulbs would fit in it.
Taking a lunch break, but am going to go ahead and get a bubble mailer packed just to see how it goes. Will report back later.