Last V-Day I got 2 dozen roses for my girlfriend at Wal-Mart for like 12 bucks. They actually looked really really nice, and they lasted over 2 weeks. One thing with Wal-Mart Roses is they haven't bloomed fully yet, so if you buy them about a week ahead of time, they will be fully bloomed by V-Day and look just as good as those $50 from 800-Flowers.
(BTW: Before anyone calls me a cheap b^stard, I'm a poor college kid I can't afford anything but wal-mart stuff

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Edit: I've bought lots of flowers from Wal-Mart for different things, they are always cheap, always look good, and live forever.