i would also call around to local bakeries and ask what they charge. i live in Savannah, GA and the cake prices out here are outrageous! for tiered cakes like wedding cakes most charge per serving which is $4 for buttercream and $6 for fondant per serving (serving size 1"x 2″ × 4″). i don’t charge THIS much, but i do make my pricing competitive. if you need help figuring out how many servings are in each tier i use this cakulator :)
hope this helps!
P.S. i also think $250 is too low!