How to get a development under contract?

[Kristina Mcleroy]

I do virtually wholesaling on smaller commercial units. I reached out to a seller that had 2 three fam homes I was interested in wholesaling. When the seller and I spoke ,he said he no longer is the owner of the homes I was inquiring about, but he does have a development he is wanting to sell. The seller also stated he wasn't listing this, nor was he working with anyone else to sell this.This is unfamiliar territory to me, however, I do have a network of buyers I am sure may be interested and would like to get it under contract. My question is what type of contract will I need for this development? Also is there a formula to use, and make sure I am presenting my buyers with a deal? Thanks in advance!