We're reported to have a 150m transfer budget. I'd hate to see more than 30m of that go to Grealish, who would be a squad man for us. Spending less than 120m may not allow us to fully address our needs at RW, CB and DM...unless Woody pulls off some serious magic, but that seems highly unlikely.
But if Ole is given a budget closer to 200m then by all means spend 40-45m on Grealish to round out the squad.
NB: I have no expectations for getting any kind of serious cash for the sale of Lingard, Jones et al.