If a club 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 Rangers signing Steven Whitaker for £2,000,000 on a four year contract costs the club £500,000 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 is an area that hasn't really bothered St Mirren. Over the 10 years covered here there has been under £100,000 spent in total on bringing in new players. The amortisation costs are therefore tiny compared to nearly everyone else in the SPL.