Since contract pricing is likely specific to each customer it may be the case that there is no way around entering those, except manually.
For percentage discounts on other items, use Customer Special Pricing. Set up general rules around Price Groups, or Customer Categories, and then assign the Price Group or Category to applicable customers. This way the pricing arrangements are only entered once.
Another approach is to create your contract pricing in a spreadsheet and then right click and Import the contract pricing into the system. However, it depends on which version of CAPITAL you are running. Older versions may not have the external import feature.