Depends if it were to be a going concern!

If not, then it is worth the realisable value of all Peter's assets.

Assuming they were to continue running it, then it would be the profit Peter makes from the advertising, less the costs of running it discounted into perpetuity (this would take account of any synergies created due to the use of duplicated assets / costs by the potential buyer). This value could be adjusted up or down, to take into account the risk associated with it. (I.e. if Bon Jovi were to break up, the value would drop considerably).