Selling Sane would fund this and sort out the foreign player quota we were hampered with in the summer.
Sane is as good as gone (and has been since the summer, when we should have sold him and replaced him with a CB), so there's no point faffing around when our glaring issue is at CB - not on the wings, where we are stocked enough as it is.
I'd much rather we sign a genuine world class player like Koulibaly for an extortionate fee, rather than Soyuncu (for what we essentially be a similar price). He may be a lot older, but he's immeasurably better and would instantly give us the best CB pairing in the world alongside Laporte.