Nylon tack always worries me because it doesn't break if the horse gets tangled or caught on something. I prefer biotahne/beta. I get my stuff from Two Horse Tack and have been really happy. They can do all sorts of colors and have great prices, and are also doing a sale for the holidays with code 12DAYS get $10 off orders $100+.
I like Weaver Leather nylon tack and even Big Horn puts out some decent (and decently priced) nylon tack. I bought a breast collar from Weaver and was very impressed (and I am exceedingly hard to impress). They also carry a rather wide variety of colours.