I also love purple fabrics and have found that Debbie Beaves does, too. I have many of her purple fabrics and am very happy with the quality of them - RJR fabrics.
You can visit her website here:
http://www.violetpatch.com/shop/
Be sure to check her "Going, going, gone" section for 4 pages of 50% off fabrics, some as low as $3 a yard!
Otherwise, you can search here:
http://quiltshops.com/
for purple fabrics, too.
I love the design you've shown here. I'm sure whatever fabrics you choose with make for a lovely quilt. I hope you'll show us what fabrics you find and keep us posted on your progress.