A fireplace is a good selling point in a home. Putting a dollar amount on the worth, however is difficult. But I think the bigger issue here is if you have a part of a home that is not functioning properly, you will have to disclose when selling. With the market now, chances are a buyer is going to make it part of a negotiation and take more than $2500 off their offer price to fix it. Or they will have you fix as a part of the negotiations. Either way, you could get stuck with it. $2500 may be better spent other places, but it isn't worth losing a deal over. I always encourage sellers to fix everything in the home. You don't want an inspection killing your deal or reducing the price even more. And with renters, the other comments are right - how do you know they won't try to use it.
Before you make a final decision, I would make sure you are getting enough opinions and prices on the repairs. There are some prefab options that are not woodburning that would give you a functional fireplace and are less expensive. Good luck and good question - a lot of people don't think far enough ahead regarding resale.
I think you have 2 issues. First you have an unusable fireplace that you have to stop renters from using, or convince buyers to take on that project. Second you want to spend good money -maybe chasing bad. Will the $2500 not be better spent on a neglected part of the home (kitchen or baths)? You won't see dollar for dollar back on your fireplace investment. If fires are important to you this winter... live life and enjoy!
Your other solution is offer money to buyer to fix the fireplace/ chimney issues. Get 3 contractors' estimates. This way you won;t spend cash until you have a buyer in hand.
Best of luck,