You have the option to pay £400 for something now with a risk that it will not happen and you will lose the money. However, if it DOES happen you will need to pay for it but the cost of it may have increased to around £700.
Do you pay now and risk losing £400 completely or wait until it’s certain but run the risk of it costing a lot more?
Chances of it happening are hard to judge. Maybe 50/50 for ease!