It probably isn't finances that this will boil down to. I'm not sure how easy it will be to get a work permit for him for starters. We may have to buy and loan somewhere in Europe (hopefully in a wiser move than Zuculini made whether his or our fault).
Atletico have Simeone and a track record at developing players. That might be enough for him. It's all quite quiet though and I've only seen murmurings about our interest. What gives me confidence is that we've finally seemed to realise how fruitful it is to invest in the South American market. How many players have come over to Portugal/Ukraine for peanuts then been sold for huge sums. He might cost more than the usual transfer from that part of the world but he is a very talented player and a big improvement on Fernando.