I read at cdrinfo that Mitsubishi is coming out with dual layer media by the end of may (in Japan anyway). Don't know about the US, but they say it'll be like $12 US per disc. Ouch! I'm sure the burners will be very expensive at first also.
Personally I'd wait until they become more common and the price will plummet, it always does. I know some die hards will rush out and buy, just to try it, but be ready for it to take a bite outta youre wallet. I haven't even bought a regular DVD burner yet. I knew these dual layered would eventually come out, the ones they have now are only like "half" of a DVD burner. Just like anything, they feed it to the public one step at a time, just to milk all the people willing to pay ultra high prices, bastards!
They coulda came out with dual layer in the first place, but they wanted to wait until they made a few billion from everyone buying a single layer burner.
Just my opinion