If United sign a player we generally know how much has been paid in transfer fees, the figures from www.soccerbase.com are a good source.

The club has to pay the transfer fee to the selling club. In the club accounts it then has to report how much it views each player's worth has declined each year. So for example Lee Miller joining for £225,000 on a three year contract costs the club £75,000 per year. This is what is reported as 'amortisation' in the club accounts. At the end of the contract the player can just leave on a 'free' so he is viewed as potentially no worth to the business after that.

This only covers the costs for players bought in. So Gary Kenneth, for example, does not have any effect on the amortisation costs of the club, as he was never bought from another club. Also once a player has finished his initial contract he stops being counted.

The annual amount the club are paying out for players shows a decline from 2000-2001 and is unlikely to rise. Comparing with Aberdeen who have a figure of around £200,000 for each of the last five seasons  shows that the figure for United is pretty normal.