I don't see Real Madrid selling Bale to us unless the number really does get close to 120m, but the unexpected can never completely be ruled out.
Among other things, we're lacking speed and power, which Bale has in abundance. I worry, however, that if we do end up spending 80m or 120m on Bale that we'll miss out on the quality striker that we actually need more than another winger. Bale isn't just another winger, but I'm confident in the job that Di Maria can do next season -- assuming, of course, he remains a United man -- and see Januzaj breaking out of his sophomore slump to have a great season. And Young has been a pleasant surprise this season. Valencia isn't the offensive force he once was as a winger, but he's not ready to be put out to pasture just yet.
For me, the real question is that if we bring in Bale don't we necessarily have to sell Di Maria? It seems to me we would. That might be tthe best course of all action for all parties involved, but it's something to keep in mind as we dream up hypothetical starting XI squads.