There are several options for putting forth an offer to purchase: 

a written purchase agreement

an email or letter detailing the terms

a letter of intent

I generally don’t like to start with a purchase agreement, as commercial contracts have so many legalese that most people may get lost in the language. Residential agents do use contracts; however, their contracts are usually provided by the multiple listing services, so they are fair to both parties. Unlike the residential world of real estate, there are no laws protecting the buyer or the seller of a contract in the commercial world. 

A letter outlining the basic terms of a contract can move a transaction along. However, if neither party signs the agreement, then it isn’t binding. 

I prefer to use a letter of intent. It spells out most of deal terms, including the price and how long the two have to negotiate a contract that both parties consider to be fair. The seller and buyer both sign off on this document. A contract isn’t entered unless a meeting of the minds occurs.