I have used DVD R DL discs on a few occasions and have found that cheaper brand discs will give you a complete set of coasters for your coffee table. Verbatim discs on the other hand produce flawless results every time (no coasters so far from these discs), these discs will also last longer and are more durable against scratches etc... than other brands.
So other brands may be half the price, but only half the discs will actually work (when using DL)