My kdHDR1is good however I want to extend the reception a bit. I have a stock antenna and it's OK but I'd like better reception.

cc crain has this
http://www.ccrane.com/antennas/auto-antennas/full-replacement-auto-antenna.aspx but that's discontinued...I'm not sure what the replacement will look like.

I saw some cheap thing at walmart but I don't think the build quality is nearly the same.

I found one that works well. In case anyone else is looking for one.
It's sold on Ebay. Type this in the search field and your there.

Fuba-VW-Antenna-Combo-AM-FM