No way is that lame! A movie and lunch is a great surprise birthday treat.
Paying for lunch and a movie for ten people could be pretty pricey, and it may not be practical to pay. I would suggest asking everyone to pay if they're able and covering anyone who can't-- except for your boyfriend! Make sure he gets covered; no one should have to pay for things on their birthday. (Particularly when it's a surprise.) You'll find that this is the way things usually go with celebrations as you get older-- particularly when you're the bar-faring age.
Anyway, good luck and have fun! I hope your boyfriend has a happy birthday (I bet he will, you're doing a very thoughtful thing by throwing him a surprise party!)
