Well, 25GB BD-R discs are $10+ each, and 8.5GB DVD+R DL discs are ~$1.50, so you're looking at more than twice the cost for the same amount of storage. The write times for a BD-R at 2x and 3 DL DVDs at 8x are pretty close. Also, Blu-ray burners cost about 10x as much as a DVD burner. But, Blu-ray discs are more durable than DVDs, it takes a lot more mistreatment to scratch a Blu-ray disc. If going Blu-ray is cost-effective for you, why not go for it? I'm personally going to wait a while longer while the prices keep falling and the speeds keep increasing.