cost for a medical for a US aviation license is thousands
In US when a Medical Certificate is required, the airman must use an "Aviation Medical Examine" (AME). That is a doctor that has applied and been designated by the FAA. The fee charged is at the discretion of the AME, usually between $150 - 250, depending on the local economy. The problem is, if there is a disqualifying factor, then the airman must submit more documentation or test results, that can result with additional expenses (depending on the test, a lot of expenses). This is the reason many are choosing to not renew their medical and fly under the Sport Pilot rules in qualified aircraft. (In order to qualify to operate under Sport Pilot rules, a pilot must not have had his medical certificate revoked)

Ralph