a new turf field costs right at $1,000,000 now.  They will tell you up front not to expect more than a 10 year life cycle out of it.  So, you'd have to spend $100,000 a year on a natural turf field to justify the cost.  and that is at today's cost.  10 years from now, a new turf field could cost $1.25 MM or more, given inflation over that ten year span.  so really, a natural turf field would have to cost you $125,000 a year to justify the cost of a turf field.  if you're doing it purely on a cost basis.