Before entering any negotiation, always know your best alternative to this deal. Your best alternative could be paying full price, it could be purchasing an item from another vendor or not buying the item. Knowing the best alternative prior to starting a negotiation allows you to negotiate within your limits and know when you should walk away. If you know you cannot pay more than $50 for an item and the seller said $75 is the lowest she will go, then you know to walk away.