My L11 team just signed a quality 63 free agent for salary about 4K. I thought it may be a super fast trainer. After I trained him one round of all 3 types of training, he gained 1 skill point and his quality just reached 64. At the same time, his salary immediately changed from about 4K to 1.07M!
I believe that this is bug that the salary was not accurately shown during auction.
BTW, he is still a very fast trainer. But I will sell him soon because I have a 5* player waiting to be signed, and I sign this free agent because I have this temporary free player slot.