If you are not borrowing against the land to buy the land, you might be able to use the land as collateral, but in this market, that might be tough.
Crowd sourcing is an interesting concept. Is there an active amateur wine making presence in your area? You could incorporate, and then sell shares to people, which would entitle them to come help and then get a deal on wine. Think of it as wine co-op, or wine club on steroids. It would take some bookkeeping, but could be fun. Just make sure that you control 50% +1 of the shares so you don't lose control. Once the winery is successful, the shareholders get dividends in the form of wine, $$ or both.
I know one winery around here is actively courting investors.