where to find info for negotiating NNN lease

[N.A. N.A.]

Hello,

Relative has a stand alone NN property (drug store - national tenant) and lease is currently being renegotiated. I am in a small market - central NY. No growth. Believe store to be reasonably good performer. Not really any good options for tenant to relocate store - all seem quite a bit less desirable. Building is older. Struggling to figure out what is a good lease rate - I don't have a whole lot of information to go on - obviously tenant knows what they are paying everywhere. Not a ton of commercial property nearby to compare. Current lease rates are significantly higher than nearby strip.

Ideally would like to figure out what a comparable store would be paying in rent but not sure how to do that. Any help would be appreciated.