I found this post --> http://heart-of-light.blogspot.com/2008/08/wedding-weekend.html
If you scroll down, you can see beautiful butterfly centerpieces. I think fabric flowers can be beautifully coordinated with them.
I had a DIY wedding, too. I made my wedding dress(http://www.craftster.org/forum/index.php?topic=305499.0), and my sister made me a veil & accessories. One my friend who is a graphic designer made invitations, programs, and thank you card as a wedding gift.
Regarding flowers, another friend decorated the hall (a restaurant) and made bouquets for me and my bride maid. We went to local flower wholesalers the day before, and bought 12 bunches of lepto, some other filler flowers and some roses to decorate the hall & the wedding arch, and peony & ranunculus for bouquets. The total cost of flowers, tulles and ribbons was about $300. That was it. She borrowed glasses from the restaurants and made center pieces. Since our ceremony and the reception was done in the same space, we saved a lot of money than decorating two spaces. Lepto is usually used as a filler and very cheap. Since I was going for a wild flower concept with the flower decorations, it matched well. If you are going for the rustic barn concept, using small flowers that usually used as fillers will go with the concept well. Usually, those fillers are much cheaper than the ones with large flowers.
Though I went for the cheaper choices for the decoration, we went for the expensive side for the bouquets, because I really wanted a bouquet with peony & rananculus. Since only a small number of flowers are needed for a bouquet, I kinda pampered myself for that
Here are some pictures of the bouquets and hall decorations. I loved how it turned out.