If one is patient one can find DL +R DVDs here for under a dollar (Canadian) per disc. It isn't cheap but it's at least reasonable.
The first blank CD-Rs I bought were in the $1.50-$2.00 range so I don't find the above price to be too ridiculous.
Obviously, if you can use single-layer media instead, it's a lot less expensive and often of higher quality. A person has to make the choice based on the circumstances. Sometimes the extra expense of DL media is justified.