Nba Free Agents Dataset From The Past Few Years

I need a dataset with all the free agent transfers with their new contract from the past years. I’m doing a proyect where I try to predict the new contract for free agents based on their performance from the last season, I’ve already found a dataset for the performances, but I can only find the dataset of free agents from the last season, and I need at least 3 or 4 seasons to have enough training volume