The deal over here is, you have no business selling baby formula ANYWHERE if you are not a retailer buying directly from a brand or brand authorized wholesale distributor. (AKA you have a legit business!)
There are FB groups for selling and trading formula. You can't sell it on marketplace, but I'd try the formula groups. You can also ask in local mom groups if anybody wants to sell or trade for the kind your baby does tolerate.
If you have unused formula that is factory sealed and prior to its expiration, visit Food Finder to find a food donation site near you. Be sure to ask the organization whether they can accept formula donations before dropping off any items.
To submit an offer on a FSBO home, you can write up a generic sales contract, go through an attorney, or hire a real estate agent. Generic sales contracts may not contain specific language for your state, and may not have enough protections for you (or the seller).
If you are interested in a home that is listed as a contingent short sale, you can still view the home and make an offer. However, your offer will usually be put in a "back up" position and will only be considered by the bank if the first buyers decide to terminate their contract.