Upon occasion I buy a bit off of ebay. Not with the intention of continually using it, but to see if that type of bit does what I want it to do. If it doesn't, I stick it away, never know if it might come in handy one day. But, if it does work like I want it to do, I stick it away, then go out and buy a decent (more $) version. Beats the heck out of buying a pricey bit, then finding out it doesn't do what you want.