is there a cheap version of O2 sensor often used on dynos?

[BLINGMW]

What do you call the tailpipe probe they use on dynos to get the AFR? I'd like to put together a little wideband controller and sensor, but it's just not going to be useful unless I can just stick it in the exhaust exit. I guess if a cheap, small version doesn't exist, I was thinking of making something kind of like this with a heated sensor:

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though it appears he completely blocked the exhaust with that thing... so some improvements come to mind. But even better, I'd just rather buy one if it's already out there.