Flowers is the only main thing you can buy a girl with that money and maybe some chocolate. Thing is, they always want something specific in terms of material so you never know what to get her.
A lot of People are saying roses, but I disagree. Roses probably arent her favorite flower, and they are so cliche. Get her something that matches her personality, for example, if she likes to write, get her a journal and nice pen. It doesnt really matter what it is as long as it is something more off the wall, something that you put a lot of thought into. No roses, dude, seriously.
Hire a Poet Online here on DP and get a nice little romantic Poem written. And take a Single Red Rose along with the Poem and give it to her while you are reading the Poem Out. Considered a Box of Chocolate's ? Clothes!.. Girls Crave Clothes .. Go out and get 2 nice look Tees. Or Lingerie?! .. that's what i am giving my Gf next.. don't even need an occasion to gift her that. And i am taking her along to Choose
This guy's got it. A single rose is an excellent idea (I wont even get into how cost effective it is too lol). edit-apparntly I was late in the advice, LOL, well let the future questioners look here and say "thats what I'll do!"
Depends what the girl means to you. The best gift could cost nothing at all, just being there. I think flowers is the worst gift of all they die to quickly, get something that would last.