If a team buys a player out, he cannot re-sign with or be claimed off of waivers by that team for one year or until the end of the contract that was bought out, whichever comes later.
How can teams afford to sign free agents in the middle of the season?
Only two NBA teams are currently below the salary cap. Teams must have a total of 14 players on their roster when the dust clears, and if you see teams trading minimum-salaried players for nothing, that is often why. If a league-approved doctor deems that player unlikely to be healthy by the end of the league year, the team is granted a cap exception that can be used in free agency or trades worth half of that player’s salary or the Non-Taxpayer Mid-Level Exception, whichever is lower.