GRP cost guarantee refers to a contractual agreement between a media buyer and a media seller, where the seller guarantees a specific cost for a set amount of Gross Rating Points (GRP) for an advertising campaign. This means that the buyer will only pay the agreed upon cost, regardless of any fluctuations in the actual GRP delivered. This type of guarantee provides a level of financial security for the buyer, ensuring that they will not exceed their budget for the campaign. It also incentivizes the seller to deliver the promised GRP, as they will not receive any additional payment for exceeding the guaranteed cost. This type of guarantee is commonly used in the media industry to mitigate financial risks and ensure transparency in advertising transactions.