Why are DVD+DL so much more expensive than DVD-DL?

[chiphead]

I see on Rima and Meritline that DVD+R 9.4 goes for around $6~8 USD compared DVD-R 8.5 which goes for $1.50~$3.00 USD.

I took a gander at the FAQ section but didn't see my answer. It had some technical reasons that +R was more reliable but no financial reasoning. Also why the descrepency in size (8.5 vs 9.4)?

[hoxlund]

id like to know where you found dvd-r dl

all i see is double sided dvd-r, not the same thing

[chiphead]

Doh I just noticed double sided != DL.