(Since no one else answered) Timothy hay is a different type of grass than alfalfa. Since most of the pellets for chins (and rabbits and guinea pigs etc.) are made from alfalfa hay, you need to give chins timothy hay to add nutrients and fiber that the alfalfa is lower in. So getting alfalfa hay through your friend could save you some money, if you can find a good timothy-based pellet to feed your chins. Off the top of my head, though, I can't think of a pellet that is timothy based. Some people even feed an all hay diet and have success, so that's an option to look into as well.
When we talk about "Oxbow" hay, we're using a brand name, like "Tradition" or "Mazuri" pellets. It's a pet supplies company that offers some of the best (imo) hays available in chain stores like PetsMart. Oxbow sells a lot of different kinds of hay, including timothy, orchard grass, and clover, but chins need access to the nutrients in alfalfa and timothy grass hays to stay healthy.