@Germlat,
That's a good idea....go to the dollar store and get one, just check the expiration date isn't past.
The store brand at Walgreens is less than what Jes even posted ($12.99), I see online it's like $10.50 or something.
Even if things are tight, I would hope you could scrape $10 bucks together. Collect all the change you can find, pawn something, ask 5 friends or relatives for $2 each, sell something on craigslist, return something you recently bought and still have the receipt for, offer to babysit for someone, offer to do someones laundry, offer to clean someone's house. check out craigs list for gigs.
Like G. said, go to planned parenthood. It's income based and if you don't have much, the test would be free.