Do we need a lawyer for an international adoption?

My wife and I live in Indianapolis and want to adopt a child but have found that the waiting period to adopt children here in the U.S. is very long. We’ve found an agency that handles child adoptions from Croatia and the waiting period is much shorter. They have lawyers who work with the agency, but my wife and I are wondering if we need our own attorney to handle the paperwork and make sure everything is in order. Should we use the agency attorneys or get an independent attorney and if so, how much does it usually cost for an attorney to do an international adoption?