From narrativ's website:
"Who sets the price for my voice?
If talent is a member of SAG-AFTRA, they will have minimum prices that range from $385 for 4-week’s use to $2,420 for a 21-month use period. SAG-AFTRA talent can always price above these minimum rates if desired, but cannot go below. Non-union talent can set rates that are below these minimums if desired."
Side note: If anyone liked The Princess Bride or actress Robin Wright, she was in a little-known 2013 movie about Hollywood starlets selling their likeness rights for replication. It was kinda before its time (few years too early, I guess) and gets pretty trippy in the second half, but was a very interesting watch.