I personally would check Craigslist. Post photos of any potential chicks here for a hopeful gender ID.
Anything you bring home needs to be quarantined for at least 4 weeks to watch for any sickness. Once quarantine is over, move them close to her where they can all see each other but not touch. After a week or so, try introducing one in with her. If they get along - great! Introduce the others in a day or so. If they fight horribly, step in and remove the newbie and try again in a few days. Initially they will squabble a bit. That's how they determine pecking order. However, sometimes they take ot too far and go for blood. That's when you should be stepping in. Multiple feeders and wagerers also help when integrating new birds. That way nobody gets bullied and kept from eating or drinking.