Begin by comparing agencies based on the countries they work with and the fees they charge. Agency fees can vary, but the country fees are generally the same. Compare the individual fees charged for each service. Negotiate with an agency, ask them if they will consider your income and reduce their fee or let you pay their fees over time. This makes the overall cost much more reasonable.
Several countries require both parents to travel when adoption internationally.
Others just require one parent to travel, but the stay is lengthy. The key is finding a country that has reasonable and explainable fees and no travel requirements, if you are on a tight budget. If money is not an issue, you will have more flexibility when adopting. Your state may have requirements regarding adoption as well. You might be able to borrow against this money.