I have a contract awaiting my signature on a solid offer on one of my properties BUT I can't shake a suspicion that I'm missing something on the deal.  I purchased 11 years ago in an up and coming area of Manhattan and am now being offered 4x what I paid...

Here's the catch,  though it is a very good offer, it is still way less than the avg sales price for a 2 bedroom in Manhattan due to income restrictions attached to our bldg.  Once the income caps expire - the value of the units in the bldg will double instantly.  There is a lot of confusion on when the income restrictions expire and I can't get my bldg's management company to give me a straight answer, despite asking repeatedly since April.

My agent, who lives in the bldg, just happens to work for the company that manages our bldg.  He approached me about selling my unit and "found" the buyer.  The buyer also just happens to be a broker who works for the company that manages my bldg.   I'm worried that I'm getting hustled - perhaps they know something I don't about when these restrictions expire?  

IF that is true and I can document that they withheld information, lied, or worked together to mislead me - would I have legal recourse after the sale to sue them?  

I've asked my attorney to weigh in and she said the bldg's attorney is the best person to give a definitive answer and I've been waiting on his response since April.  What can I do to protect myself if I move forward with this deal?