This one is supposedly much better than a lot of the cheapo ELM 327 adapters that typically sell for much less. I got one of these for Christmas, but haven't had a chance to try it out, so I can't say for sure. I do know that my cheap ELM327 adapter would not allow me to clear codes on one of my vehicles.
3 camels shows it out of stock at Amazon, but it's not, according to this link. I think this is the lowest price I've ever seen.