Custom Price

I have issue regarding the custom price for every product.
for example, I wanted to enter dynamic price (according to the user purchase)whenever every user add top cart a product.
The price will be the URL like something /cart/?pr=10, it will different for each and every product.
I am looking for any hook or filter which provide me to get this price in query string and update in all process from cart to order.

Please help me on this matter. Looking forward to need a support on this. Any suggestion would be appreciated.

Thanks in advance