If he is like me most guys don't want really expensive gifts from their girlfriends they buy really expensive gifts for their girlfriends :). My girlfriend last year gave me a card with her picture inside with this little note "I won't get into details of note" and it was the best Christmas present I ever had :)
a benten watterbottle
something that they like
You can get them online.
In a trash can
"Hayd"
A good birthday present for your boyfriend is a kiss!
It has to mean something to him/you, so base it on what he likes - and look then for something cheap.
A good 19th birthday present for your 2-year boyfriend would be a fancy smartphone.
depends if they like you.
a werewolf girlfriend or boyfriend
smile by uncle cracker.
make somthing
It depends on the kid.
Burn a CD of his favorite songs, and get him an awesome watch.
tickets to his favorite band/sport team
A card or a day out with each other.
CDs and video games are great birthday gifts for a boyfriend if he is into that. How about a new cell phone?