Antoine Walker’s NBA Championship ring just sold for $21,500 … which would have been great news for Antoine, if he wouldn’t have been FORCED to sell as part of his bankruptcy case. Walker — who won the ring as a member of the 2006 Miami Heat — filed for bankruptcy back in 2010 … claiming he racked up more than $12.7 million in debts … but had only $4 mill in assets. According to court docs, Walker had to liquidate his property to pay back his creditors …