There is no legal requirement for a realtor or lawyer--you are allowed to do it all yourself. Since the main thing a realtoe does is find a buyer, you can do without one if you already have a buyer and therefore save the commission. It would be a good idea to hire a lawyer to draft and/or review the contract, so as to make sure it meets your need and protects you; the lawyer can also help with the title search, closing, etc.