Too old to man a lemonade stand?

I'm 16, and I'm duel-enrolled at the local college. The books are horrendously expensive, and my parents just can't pay for them. So to help scrape up the funds, I was thinking I might have a lemonade stand. Is that immature or embarrassing if you're well into your teens and not a six-year-old girl scout? Am I just too old to consider that an option? If I am, what other ways are there to raise the money somehow? I have a job, of course, but classes start too soon for it all to be covered by a single paycheck.