"Usage costs 10% of your expected annual savings spread over a 12-month agreement."

This is hard for me to sell. Not because it doesnt make sense, but because its damned hard to propose in my budget submission. Its equivalent to me saying "I am requesting an unknown amount based on potential savings, that we may, or may be able to implement across this financial year". I cant easily get that across during a budget submission, and it's going to be difficult to pitch at another time after money has been allocated and I have no idea if I can go through change management to realise the savings in the same billing time as any agreement.

Might I suggest you make it linked to current expenditure?