Busy weekend, sorry for slow response on this...
In the USA, there are really only three places I'll suggest first for buying Taiyo Yuden media at the lowest prices. This is historically where I've bought all of my media, including Verbatim and Taiyo Yuden discs:
We try to track some of the best current prices on TY and Verbatim discs (i.e., the best DVD blanks you can buy) at http://www.digitalFAQ.com/reviews/dvd-media.htm
And then you should also give a quick check to some of our site sponsors, who can sometimes have great sales and cheap prices on the best blank DVDs:
We also have affiliate relationships with several more good stores that stock decent blank DVDs:
... and know that we ONLY affiliate with quality merchants with quality merchandise, and not just anybody willing to share their profit. (We still have ethics, even if most websites have lost theirs or never had them to begin with).
I hope that helps you with your TY shopping!
If you have any other questions, just post them. Thanks.