Some have speculated, and it seems a reasonable take on things, that Swansea have simply bought out the rest of his Barnsley contract i.e. 2 years at £250K a year. Less than we got for Big Val but at the time he was a Head Coach in the Championship so was probably on a larger salary.
He's a relatively inexperienced manager of a third division club. How much do you expect to get for him? For context, £500k is rumoured to be 5 times what we paid to take him from Cheltenham.