Actually your 8 cubic ft bag at the local feed store is a better deal, here's the math:
1250 cubic inches converted to cubic ft is .72337962963 divide that by $2.75 (generous approximation of less than $3) = .263047138047 cubic ft per dollar.
Now take your 8 cubic ft divided by $25 = .32 cubic ft per dollar.
Now take .26 divided by .32 = .0832 ,so you get approximately 8% more cubic feet per dollar with the big local feed store bag.
I belive these computations are correct but I didn't take the time to check so if I'm mistaken someone please correct me.

Quote Originally Posted by brain View Post
That is a bit cheaper than I pay. I get 8 cu’ for $25.00 at my local feed store.