What is an appropriate gift for a re-marrying dad and his fiancé?

My dad is getting married again. That in itself is not easy. It is made more complicated by the strained relationship between my family and his girlfriend.

I feel that a gift is “compulsory” when attending a wedding. My family says to ignore that feeling, but I do want my dad happy.

Do you agree that a gift is pretty much expected? Do you think this gift needs to be large? My dad asked for, “a nice DVD”, which doesn’t seem special enough. On the other hand, I have NO money to spare at the moment.

Help?