I'm currently working on a module and i need to be able to change the product price as it is added to cart.
For example, Product A price is $25, but it is also available for $5 dollars if certain conditions are met.

I've got the product to show the correct price in an ajax popup that allows it to be added to cart, but when it goes to cart, it charges the full price.
Both prices are stored in the db, one as products_price, the other as products_price_offer.
The new pages i have built all reference products_price_offer as i want, but i just can't get it to pass the offer price to the shopping cart.

I think if i can find where it builds the array for adding to cart i can manipulate this to use the offer price instead, but i just can't seem to find it.

Any help would be appreciated because i seem to be getting nowhere fast now.

Thanks