Now my buyer Is thinking about backing out and I'm wondering what kind of legal remedy can I seek if this happens?

In any action with respect to this Lease, the Parties are free to pursue any legal remedies at law or in equity and the prevailing Party in litigation shall be entitled to collect reasonable attorney fees and costs from the non-prevailing Party as ordered by a court of competent jurisdiction"I think this should protect me.

Lead paint itself is not dangerous - it's the lead paint that is deteriorating—peeling, chipping, chalking, cracking, etc, that is problematic and requiring remedy. 

These tanks can contain anything from waste oil to gasoline, for example if there was a gas station there in the 1950's, those tanks could possible have never been removed and can easily cost 10's of thousands to be remediated.

I don't know anything about the ones you mention but I would be at least leery, if not outright suspicious, if the results were achieved by a company whose primary business is mold remediation.

If the current owners didn’t act promptly to remediate the water damage, the home will likely develop mold.Given that this issue was not disclosed and happened prior to closing, I would not put pen to paper.I would not want to live in a sick home, or one that likely will bury you in repairs costs.What other surprises awaits.

Originally posted by @Jinesh Kumar:Thank you all...Roof has some shingles off so they decided to end my contract :-D.....I will fix shingles and try another insurance company...but my agent said just fix shingles and reach out to him..he will reinstate the contract again and straighten everything out...If they were aware of the shingles and it was an issue for them, why didn't they address it with you and give you a chance to remediate before canceling your policy? 

Easily remedied in a weekend. 

One of the remedies that I'm looking into is steel beam support for the interior of the basement with a 50 foot section of the basement costing $12,000.

I’m wondering if anyone has dealt with lead paint remediation in Buffalo, NY?