That price is better than here ($3.39 just last night vs $3.89), but not great. $3.00 would be great right now. $3.19 for E85 vs $3.87 for Premium means you're going to be paying significantly(>5%) more for E85.
E85 has
72% of the BTU so even with 28.5 on Premium Gasoline, should be 20.5MPG on E85. I get 15.6 Cents per mile on E85. Still more expensive but how much is it worth to you? Myself, I'd eat the extra cost if E85 is 85% of Premium.
Never run Gasoline on an E85 tune.