Do you buy your anime DVDs as boxsets or volumes?

I personally prefer to buy mine in boxsets. I'm the kinda person who likes to marathon series, and I don't want to be left hungering for more at the end of what I have. Plus, I always found buying in 'bulk' to be a little bit more cozy for da wallet, especially when I buy series online...as the shipping can build up if I buy stuff seperately.