Dynamic pricing of products/line items with a "pricing entity"
So this first alter hook handles price on product display.

But price needs to be handled again with another hook: commerce_dynamic_pricing_commerce_cart_line_item_refresh.
This handles prices regarding current line items in cart.

I also needed to avoid combining same type of line items into "quantity groups".This works well in:

    $line_item-&gt;data['context']['add_to_cart_combine'] = FALSE;