My advice:
DO NOT GET MARRIED TILL AFTER COLLEGE!
As for the ring. $300, I think she'll say no..... That's like a grain of sand on tin foil band. just kidding. When you do get the ring though, do not go to the mall or internet!!! Go to a local "mom 'n' pop" type store that is priavtely owned. no chains, like in the mall! You'll probably be stuck with a tiny ring. Go
here to get ideas for prices. You're looking at 1/10th of a carrot. Have you looked at rings with her? My fiance would have killed me if I didn't get her a marquise cut ring with a traditional gold band, like her moms!
Have you talked about marriage with her? Not in passing, but a serious conversation?
You're going way to fast. If I was her dad and you asked me I'd say: "You make my daughter happy and that's all that matters, but you should wait till after college." I think I would have to smack you for even considering it.
Also, at a concert? OK, that is NOT memorable. A candle lit dinner that you cooked is better. A walk on the beach, after a romatic dinner? Something you do together (I did it playing Scrable, spelling out the words
"Will You Marry Me?" (They are there, just look).
I screwed up and skipped the father's blessing part, but we were like family before I proposed. My fiance says that her parents love me and not to worry. I wish I did though.