Tthe media listed in the quality guide are based off the manufacturing of the surface alone, not the coating. The coating of a disc will not change the quality. Inkjet, branded and unbranded should be virtually identical in this regard.
I'd suggest
Supermediastore.com or
Meritline.com or Rima.com for buying online.
You'll actually be pretty hard-pressed to find good inkjet media in stores. I have seen some Verbatim, Maxell and TDK inkjet discs, but infrequently. I would never get the Memorex inkjet media.
Taiyo Yuden and Verbatim inkjet media are what I would suggest you look for.