I haven't bought any, but I got some free this summer from an old theater that was being remodeled. I painted and re-upholstered them, and they look like new. You can call local theaters and see if they have any laying around.
The plastic seat bottom & top and the foam and the fabric are all new materials. I guess the metal supports and maybe the armrests are "used". They are very nice and were available in different widths when I purchased them.