Mild exception
I have found that you can go buy the most expensive blank out there, and the quality will be no different than a much lower cost reasonable priced disc.
For example, both of the brands I use regularly, I have done so for a couple of years. These are Verbatum, and Ritek. The Verbatum are generally twice the cost of the Ritek.
Now, I have tried a lot of different brands, and some have started fading away very soon after being burned (DVDPro), while others have taken a couple of years ( 3M and Apple ).
I would urg people not to take cost as the only factor, but instead, try different brands on different burners ( not all burners like the same brands of blanks ), and try to find out what other people with your brand of DVD burner have had long term (if possible ) luck with. A good source of information might be your local videographers, and there source for media. In Denver it is the 'TapePlace' .
Myself, I will pay $1.25 for Riteks 4x blanks, $2.50 for Verbatums, and $3.25 for Ritek 9.4 GB blanks. I will not pay $9 for Pioneer 9.4GB blanks, even though Pioneer makes the Apple drive I use.
I could pay much more, but , through two plus years of testing, I have found that it buys me no more quality. There is no sense in throwing money away either by paying way to much, or by using really bad discs.
Max