throw (something) into the bargain
To add something to a deal or offer, in addition to everything else or to what was already stated or expected. I know they're willing to throw extra vacation days into the bargain, but what I really need is a higher salary.
throw something into the bargain
and include something in the bargain; throw something into include something extra in a deal. To encourage me to buy a new car, the car dealer threw a free radio into the bargain. If you purchase three pounds of chocolates, I'll throw one pound of salted nuts into the bargain. She threw in a free calendar.