This post is arguably really old. Tungsten bucking bars are really popular, but I can't believe what they cost. For a while now I have been purchasing as close to the source as possible, and usually that means in China.
Can't remember where I learned about this particular source, BTW.
www.chinatungsten.com is the website, but just email email@example.com and tell them that you are looking for bucking bars. Had two within 10 days or something like that, via FedEx. I paid $50 and $46 each for the bars shown below, plus shipping, in June of 2009. The total came to $143, and they promised 18 days delivery. As I recall, the actual shipping time was more like 12 days.
Click on either image for a full-size version of the drawing.