Dynamic Pricing Overrides at Checkout API

I want to be able to override the price of a standard product when creating a Checkout via the API. Currently, we have to generate a unique, one-time product for every order because our pricing is dynamic. If we could pass an ad-hoc price parameter during checkout creation, we could use a single standard product and attach all our marketing discounts to it in the dashboard, while still setting the specific price for each customer dynamically.