A Washington residential purchase agreement is used when making an offer to purchase real estate. The agreement initiates the negotiation process.This is a basic tutorial on writing up an offer for a WA unimproved land parcel only. Send a For Sale By Owner prospecting letter to neighbors in 3 simple steps. Learn how to generate leads for your FSBO campaign. The first step is the details. Scroll down to the bottom of this section to define the purchase price, offer date, expiration date, and closing date. No need to install software, just go to DocHub, and sign up instantly and for free. Go to any local title company and their lawyers will draft a purchase and sale agreement. No need to install software, just go to DocHub, and sign up instantly and for free.