Any smog experts out there?

cudamark said
O'reileys has a Walker brand for $37. Bosch is $79. There are few others in between. Anyone have bad experience with any particular one?

Well I tend to go for Bosch, that same one on eBay is probably $52, I just bought one and it showed up in 2 days. The bonus with the parts stores you pay that little extra for a warranty most the time and that can come in handy