E-Herko is on Ebay and they are awesome.
I ordered the wrong set of O2s (My year has 2 different (front)sets based on the tranny option) Any way, they sent a call tag so I did not have to pay freight back to them and shipped the correct ones before they got the other ones back.
Their house brand of O2s seen here
Front O2s
Are $16 and work great. I was never able to use anything other than Standard brand before. They all threw a code. But these worked great. Can't beat the price either.