As far as being a deal breaker, that is up to each individual buyer. If it is not a deal breaker to you now, it may be a deal breaker to the person who may want to buy it from you in the future. In that scenario, you would be paying for the permits the current owner should have paid for.
You can ask for the permits up front in the offer (Seller has X days after acceptance/prior to closing to provide permits for all work done to [wherever there was work done]) or, put the same language into an amendment after the home inspection. The seller would then have to apply for permits, pay the fees, have the building inspector in then fix anything the building inspector doesn't like.
Best of luck.
Paid receipts, lien waivers for contractiosr work helps expedite clearing title.
Key is code compliance.
For a buyer, the lending bank will likely want to know this too. If not - their appraisor.
Frank Pearce, Broker Associate, Realty Executives-Integrity, Brookfileld