I agree with Connie. There's so much variation in pricing depending on where you buy from. I actually just got a 50# bag of mazuri 9F last night for $25 I guess that it's actually replacing the 6F for some reason but I'm not sure what the real differences between the two are.
NM apparently the only real difference is a little bit higher fat content in the 9F compared to the 6F. I usually feed the regular Mazuri rodent diet since that's all I could get for a while (had to special order the 6F) and never had any issues with that even though the protein content may be a bit high (23%)