If one has an Android phone, and searches for "repeater directory," the top search result is the ARRL Repeater Directory.

It states price: free

You then download the directory, and get the message, "If you want 2-meters and 70-centimeters, you need to pay an additional $10."  Note that realistically, the only repeaters people are interested in are on 2 and 70 cm.

This has apparently not been a hit with users. The directory is rated at 3.3 stars, out of 10, and the negative comments relate to the misleading "free."

I would suggest simply listing the price at $10, and possibly below that, note that a sample directory with no 2 and 70 is available for free.

Being straightforward with the membership and users is probably a good idea.

73,

Dick Norton, N6AA