I use mazuri chinchilla food (mainly because I can buy it in bulk at the local feed store)...as for hay I used to go with farm fresh from farmerdave.biz and the chins would go crazy for it, but unfortunately it made my asthma go crazy as well.
I now use I believe it's Standlee brand Hay Cubes that I get from tractor supply company (really cheap) and sometimes order the hay pellets from either farmerdave or wherever I can come across them when in need.