DPO + positive test?

Hello all!
How early have you guys gotten positive tests? I'm 10 DPO and my boobs are tender, I'm exhausted & emotional. My normal PMS is 100% rage, so I wouldn't necessarily chalk it up to PMS. I would like to test ASAP but don't want to waste $13 if it's too early. We don't have the $.88 ones at Walmart here unfortunately, I've looked and looked.