I work ticket prices out like this
From level
1 -10 × 1.5 = price
11 -20 × 2.0 = price
21 - 30 × 2.5 = price
31 - 40 × 3.0 = price
41 and above ×3.5 = price

This will give a rough guild to your price, if attendance is full (at home matches) put it up by 2 each time it's full,
If you see your attendance drop put it down by 1 each home game until attendance is back to full

then you will know your maximum price

but like any opponent youll face theres always 1 or 2 that youll get low attendance of regardless of price (from my eperience)