If you are invalidating a patent is their a fee? How long does it take?
To invalidate a patent, that often requires a lawsuit and all of the addional fees included (E. The USPTO has many helpful links, and you can easily find them with a simple google search.
I am not sure about the fees, but it's a mind-bending process and can take several days if companies didn't find a good lead. I was stumbling upon some case studies of invalidation searches and found an article of a company. The article shows how they cracked an invalidation case and generated a good lead. That might help you understand how the whole process can vary in time. Here you go - INVALIDATION SEARCH – HOW WE CRACKED THE TOUGHEST CASE WE CAME ACROSS Based on resources and search criteria fees may vary.
Is it a valid suggestion to simply say to consult a lawyer and see if it's really invalid, then once you've verified that, simply ignore the patent?
If their patent is a troll or not valid, your only fear is the litigation, which your lawyer has already informed you they can win.