I have imported bunches of $1 DVDs from China and Viet Nam without any trouble. Customs generally allows one per title (multiples is another story - as it makes one look like a reseller and not a tourist). I just list the dollar value on my declaration form; don't the instructions on the back say to list items only if they exceed the allowance?

Of course your brother knows that they won't work on a Region 1 DVD player, right? Gotta have a multi-region player to watch those.