I don't really understand your question.
The inspector & the Contractor are not Real Estate appraisers. Are you saying that they are giving you an opinion of value that is less than half of what the appraiser is saying the home is worth?
Regarding the fireplace, if you didn't know that it did not work & that's how you reported it on your Transfer Disclosure Statement, then you did the RIGHT thing. You're not a contractor, you never used the fireplace & you didn't know it wasn't working properly. You don't have to fix it if you convey to the buyer that the home is being sold in As-is condition.
If the appraisal came in short of the purchase price you & the buyer agreed upon, then there needs to be some re-negotiation. In this kind of market it is unlikely the buyer will bring in the cash needed to cover that difference. No one wants to pay over market value.
Shoot me an email directly if I didn't quite answer your question & I'll be happy to help you further.
Realtor Since 1996
Main Street Realtors