He may well have earned many tens of thousands of £s a week, a few years ago, but recently he's been in the Ch'Sp with Swansea and currently he's earning nothing at all. In those circumstances something like £5,000 a week might look very tasty. Personally I doubt he would be worth the trouble, but there may well be others in a similar situation where the same financial case could be made.
If we could get Bony in on a one year deal for 10kpw or less we'd be mugs not to go for that. An out of sorts Bony would still have far too much class for the 3rd division.