Apparently there were about 3 IG-88 models.  The sentient one copied its prog. into the other two and basically the droids themselves were destroyed.  IG-88 did however manage to upload himself into the 2nd Death Star and basically take control (ie BE the Death Star), but of course it was destroyed too. 
 
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which of course left his empty shell of a droid behind. 
as per what he would do with the credits, well he did have a ship, the IG-2000, he would have to upkeep it and buy weapons, repair parts for himeslf and ship, fuel for the ship.