A really good source for new slipcovered furniture is clubfurniture.com. They are good quality and relatively inexpensive. It just won't have that tag that starts with a P and B...but it's basically the same thing. You can pick your fabric from their choices. I like their white linen fabrics:
The below chair came from craigslist, and I hired a local seamstress to make the cover. I chose a wispy lightweight linen which turned into a really bad idea. After only two years, the arms are becoming "distressed". Not the look I was going for in this particular case.
Remember my post about the "perfect chair"? I had many inquiries about the slipcover. It came with this darling slip in white linen (thicker than the above linen!). I love how it is cut to hug the wooden lines of the chair. I'm sure the ties were meant to be bows, but I personally prefer the ballet shoe look.
Slipcovers are not just for upholstered pieces. Here I've made some to dress up some stools (and hide an imperfection). You can read about how I made them here.
I couldn't imagine living without slipcovers. If they ever go out of style I've resigned myself to being unfashionable. :)