If these reports are true, Fox has picked his spot. A spot that can take him in for NOTHING. Sorry, but this is likely in the hands of Fox's folks now.
If the Spurs want him for NOTHING, then the Spurs can wait two years while he plays out his contract, waste those years of Fox and Wemby developing chemistry, make sure they clear enough salary space to sign him outright, and hope that in the meantime Fox doesn't change his mind or get badly injured.
Or, they can make us an offer that at the very least matches the market offer from any team not called The Spurs who wants to take a Webber-style risk on convincing Fox to stay. That way, they get Fox for certain, and they get to have him and Wemby develop chemistry before Fox's window closes. Their call.
We don't have to take an insulting offer because Fox only wants to go to one team.