http://maryjos.com/ has a huge selection for $14.98/yard. This seems to be the best price around.
It used to be most places were selling it for $16/yard (or $4/FQ), mostly at shows.
When I was last in MaryJo's in June 08, I was thrilled to see a table of a gazillion colors ...and a price of $10/yard.
I bought a lot of my dupioni stash from G Street Fabrics. I see their prices are now up to $22/yard. I don't remember how much I paid but I KNOW I didn't pay that much.
If anyone knows a lower price than the $14.98/yard, please chime in. ;-)
I prewashed my silks (mind you, I NEVER prewash my cottons). I zigzagged around the edges and just tossed it in the machine. I don't think I used the dryer.
In some instances, I've used a fusible interfacing to cut down on the fraying - it is very, very annoying. I found it was easier to work with and reduced all the wispy silk fibers floating around.