It's actually all very simple.
Wenger is bidding on Saurez to drive the price up for Real Madrid. Real realises that they're going to have to spend a lot of money, so while they have to spend so much they might as well buy Bale.
They pay Spurs 100mil for Bale. Spurs needs a new Stadium and they use the R100mil + a R100 loan to buy the Emirates from Arsenal.
Wenger takes the R200mil and buys Messi.
R100mil is only 10mil pounds. That's only 1/3 Andy Carrolls.