How about making an edition to the image of the food? Adding the costs beneath the image of the types of fruits... I'd do it and post here if I had a working computor. The iPad's image editing s****s are a bit limited, lol.

It should be divided in:
ammount of food per silver coin (A) - which ones are cheapest
Ammount of food per minute (B) - fastest ones
Cost of one piece of food (C) - ratio of price divided by time (in one minute) (rounded up slightly)

Impruberries
A - 60
B - 12
C - 5

Bufbeets
A - 40
B - 6,67
C - 6

Firapples
A - 10,83
B - 0,83
C - 13

Pumpwings
A - 14,22
B - 0,75
C - 19

Eliteleeks
A - 16,92
B - 0,677
C - 25

Scalypears
A - 18,57
B - 0,58
C - 32

Upgrapes
A - 80
B - 10
C - 8

Rushrooms
A - 86,66
B - 5
C - 18

Diamondates
A - 93,75
B - 2,66
C - 36