Just a very quick overview on this.
Let's say a player signs a five-year contract on £100k a week. Papers report (assuming someone leaks the salary) £5.2m a year.
Over the life of the contract it'll probably cost double that.
Pay structure is more like £85k a week salary, £15k image rights.
The salary is subject to NIC and apprenticeship levy, so it costs £5.1m a year.
The image rights don't attract NIC (that's why clubs like them) so they cost £0.8m.
Agent fee will be something like £3m, of which £1.8m (50% +VAT) is for the player's account. In practice, the club pays this, and the tax on it so it'll cost £3.9m p.a. over the first 3 years, with £1.5m for the club's account which is subject to amortisation (not a salary cost).
Player probably has performance bonuses worth £1.5m-£2m (costing the club, an average of £2m p.a. including NIC).
So the actual annual cost is probably more like:
Years 1-3 (with agent cost) £5.1m + £0.8m + £1.3m+ £2m = £9.2m (more than twice what's reported).
Years 4-5 (no agent cost) £5.1m + £0.8m + £2m = £7.9m.
Over 5 years that's £43.4m (against £26m implied by the press reporting).
And that's assuming the player doesn't negotiate a new, improved deal.
EDIT - amended for agent fee - I put the full amount in for years 1-3, rather than 1/3 each year.