The initial investment for your greenhouse ranges based on what you intend to grow, and at what scale.The more automation and equipment you intend to use, the more money it will cost. Greenhouses are often investment intensive, requiring a fair amount of capital before seasonal profits begin to come in.
Outside funding may be a possibility, especially with a well-designed business plan to show to potential investors. Create a plan that describes your vision, the local market, operating plans, your products and services, and marketing strategy.