The actual current asking price is 1.6 million, so if they meet their goal with the matching funds from New York State, they would be clearly above this with 1.7 million dollars. (The Indiegogo fee is only 4% at that point.)
It should be noted that they will need additional money to actually turn the building into a museum, so that where any money beyond the amount needed to buy the property will go.
I would view it as unlikely the other developer will win by raising the bid because the company in question is not required to necessarily sell to the highest bidder, and if they refused to sell at the 1.6 million amount and even a bit higher, the company in question could be looking at boycott threats and a large amount of bad publicity if they don't sell the property to the foundation. Under these circumstances, local politicians might suggest there could be permitting issues and other regulatory problems with tearing down the historic property as the developer desires in order to scare them off.
If its truly not possible to refund the money and the sale does not go through, presumably the non-profit in question would dedicate the money towards creating a Tesla museum and science center somewhere else in the New York City general area.