It is sometimes possible to find enrolled tribal members who offer ceremonies off the reservation to non-tribal people. In almost every case this is being done without the approval of the tribe by someone who would not be authorized to conduct the same ceremony back home.
If the ceremony being offered is the traditional ceremony, the tribe almost always disapproves; if it isn't the traditional ceremony, the tribe will always be quick to point out that the person performing it doesn't represent them, and that he or she shouldn't be embarrassing the tribe by de-frauding outsiders using their tribal identity.
If you really want to meet Native American elders and participate in their ceremonies, you'll need to choose a tribe you want to connect with, then go to their reservation and gain their acceptance. Most tribes have had negative experiences with outsiders who want access to their ceremonies, so they're understandably hesitant and the process of gaining acceptance can take many years.