A while back, they replaced a broken bit free of charge even though it was out of the 30-day guaranty period. The broken bit aside, these were the Holbren brand bits, and they seem to have a good quality/price ratio and a good reputation. Whiteside bits are very nice, too although a little more pricey AFAIK.
Free shipping and fairly fast, too.
I have no affiliation with them, just relaying an email I got this morning.