Lowest cost USB Wireless Adapter

I saw the long list of approved USB wireless adapters.  Any recommendations of the cheapest one in the group?

Also I assume the wireless adapter is need to access your wireless router.  Is this correct?

Thanks.

Yes, you need a wireless adapter to connect with an wireless router, but only in WDTV Live and WDTV Live Plus.

I finally bought Linksys wusb100. It works fine.

The most IMPORTANT thing is that the model, version and revision match exactly with one of the list, not only the price.

Good luck!

I think I have found a cheap option.
As wireless router I’m using a TL-WR941ND and in the media player puts a USB Adapter TL-WN821N.
This combination worked perfectly on first go through two reinforced concrete walls throughout with an adequate transmission rate.
The USB adapter puts but not directly in Media Player, since it is a bit too large for the available space. So I have a USB cable between.

The price for the USB adapter in Germany: € 13.90 (Amazon).