Know that info but keep it to yourself! Never bargain to a payment because the salesman will always meet that number and you will overpay for the car!
Bargain on the price of the car compared to what others pay. That info can be found at KBB.com or Edmunds and similar. If the list price is $25,000 but most buyers paid $22,000, that is your target price. If you tell the salesman you can afford $350/month, they will hit that target, and you will be paying on the sale price of $25,000. Don't fall into that trap.