A lot depends on the state where the property is located. Some require an attorney; others do not.
Most homebuyers can generally handle routine real estate purchase contracts as long as they read the fine print and understand all the terms, but pay close attention to any clauses, contingencies, and other special considerations that will allow you or the seller to back out of the contract.
When in doubt, consult an attorney. Ask relatives and friends for recommendations. Call to inquire about their fees and to check their level of experience. Expect that more seasoned attorneys will cost more.