It is simple, you need to join the MLS for your projects. You need to figure out a way to make the business work. That might mean charging the client for the MLS costs for one project.
There area markets where you have to be a broker to be on the MLS, so appraisers need to also be brokers or agents of a broker. Additional costs there, but there is less competition for appraisal services.
Keep in mind you need to have experience for FNMA projects in the subject market areas prior to doing the project, so if you don't have the experience, you need to turn it down anyway.
This is the real reason why certain areas have few appraisers, same as other service industries. You might have two local farriers and zero appraisers in your rural area. In a big city too many appraisers and no farriers. Supply and demand.