Use custom price for Cart and orders

[923290_1508425036]

Hello everyone, I have created a form to enter a custom price for a product, it is saved on the db as "web_price". I would like to be able to use this price for the entire purchase process from the site, but as I have several modules (amazon, ebay) that use the original price of the product, I would like to keep it that way. Can anyone give me any suggestions?
I have tried creating a front module for the price override on Cart, using an override for CartController but the price does not change (despite printing the cart with the changed prices to log).

I also thought about using a specific price for the product, but this would also change the price used by the modules (ebay, amazon), or is there a different way?

Thanks in advance.