I am helping a PhD student who makes constant reference to an Internet application he is studying by using a string of noun phrases, specifically
...its ease of use, general applicability and free of charge
By free of charge he obviously means it costs the user nothing, but it doesn't fit with the sentence grammar.
My question is how do you turn free of charge, which is adjectival, into a noun phrase? The freedom of charge is just wrong, and though free accessability works it also has another distracting meaning. Turning free into a gerund doesn't help in this case either.
In previous cases I've suggested to him a restucturing of the sentence grammar, but I'd be interested to hear some better suggestions.