Wow. A Backyard Wedding just posted the most brilliant, budget-friendly idea I've read in a while. Here's what she said about her DIY flowers:
"A few weeks before the wedding I posted an ad on Craig's List asking if anyone in the area had local roses they would let us pick. I thought it was a long shot, but a woman who grows roses and other flowers for floral arranging competitions responded and said we could pick whatever we wanted from her yard! She was going to be on vacation, but she left out buckets and clippers and everything for us."
It didn't end up working out (due to a losing the address and not being able to get in touch with the vacationing woman), but it's still a fantastic idea.