I've found the following example (WooCommerce: Add product to cart with price override?) which lets the user add a product to the cart. However, it hard codes the prices directly on the cart itself.
Is there a way to make adjustments to a product instance i.e. costs, append additional user input, etc. and then add the product to the cart?
Thank you very much for everyones help.
Edit:
Having another crack at explaining, as doublesharp has pointed out it's not quite clear.
Joe clicks on a product, he then chooses various options on the product form which then calculates a custom cost after the 'add to cart' button is clicked but before it is added to the cart.
These options need to be completely custom as the calculations involved are outside of scope of a woocommerce 'variable product'. What I'm trying to achieve is the customer being able to add multiple instances of the same product with various costs and info associated with it.