Tony&Lyndsy

Has anyone else run across the issue of having to pay a fee in order to access a geocache? For example, there is a cache hidden in a fort in my city. It's a national and protected site, but there is an entrance fee in order to get in and take a tour. The cache is hidden inside, with permission of the operator (as they have placed it), but in order to get in to grab the cache, you have to pay. Anyone else experience this? Is it allowable? I can't find anything to the contrary.