The commercialization of yoga is a double-edged sword, and it behooves us to remember that yoga is ultimately about spiritual growth, not being trendy or developing a hot "yoga butt." The yoga gurus who brought yoga to America practiced in loinclothes on woven blankets. They did not have fancy yoga mats, special moisture-wicking yoga clothes, or even yoga blocks. They did not have air conditioning - which is what inspired Bikram to create his "hot yoga," so that we could experience a more authentic yoga practice.
I do, however, love to treat myself with nice yoga clothes. I used to just buy the cheapest stuff I could find - whether it be from a thrift store or bargain basement. But then I started doing a little better financially, and getting a nice yoga top (still at a discount, usually) is not a bad way to treat yourself. Unlike some women, I have no interest in $500 handbags, or manicures, or botox treatments. When I buy myself some nice workout clothes, it helps inspire me to get out and go to a class. I open up my closet and I'm confronted with messages that say: "Exercise, do yoga."
Yoga is not the only exercise that has spurred entire clothing lines. Step in any Zumba class and you'll find students wearing workout tops emblazoned with ZUMBA on them, special Zumba sneakers, and even belly dancing accessories so you jingle while you wiggle your rear. I took a class with one Zumba teacher who was decked out from head to toe with bright, neon and black Zumba gear. (She is a great teacher, so deserves to have the gear!)
Yet, it can be far too easy to get caught up in the consumption of yoga gear instead of yoga practice. New mat materials, high-end fabrics, and creative designs in the realm of yoga towels provide lots of yoga toys to buy and play with. At some point, though, you realize you have enough and it's time to get back to the business at hand - doing yoga.