About $20 - 25 depending on the friend. I try and get those Lego sets that are around $29 on special when they are $20 and have a supply of them for parties. Lego is always a hit and can be easily returned if they have the set already. We are Costco members so I have a large roll of double sided wrapping paper and colouring cards that wrap all presents.
I only look at DS presents to check I'm not being too stingy!