Subsidy in my state is 50%. i.e. for 10 gunta(,25acres) 9 lacs. Govt subsidy is 4.5 l. I am not sure Govt pay in advance or you have to pay first and get sanctioned later. Please discuss with your horticulture officer.
Add bore well +5-7 Hp motor cost. Generator or Biogas plant Cost. Running Capial for first 6 months.
I dont have experience of a poly house. But I have read people saying the break even is in about 1.5-2 years.
My sincer suggestion is dont jump into investments suddenly.
Phase1 Try grwing Capsicum or flowers with shade nets understand the behaviour of plants for one season. You can lear lot lessons in this period.
Phase2.You can plan poly house .