I pretty much only eat asparagus in season, so my farmer's market is a great source. It gets really inexpensive for a few weeks.
That said, I think I've seen organic at the grocery store, so you might check out a variety of stores to see if they have it.
You can make your own broccoli sprouts - just follow sprouting instructions with organic seeds. Overall, it's going to be cheaper, and you can make them in the quantity you need.
Sprouting instructions and a supplier for organic seeds:
http://www.sproutpeople.com/seed/bro...uters.broccoli