How to deal with this landlord?

My landlord, a sponsor of an apartment building (meaning he owns most of the apartments in the co-op building), just told us that he does not want to renew our release any more. The reason I was given is that he wants to sell the apartment. This is not completely true. I found out that the landlord is doing following trick: rent out the apartment, then tell the tenant he does not want to renew the lease (sub-lease) any more and gives you the option to buy with riduculously high price (at least 20% more than other building). After that if the tenant does not want to buy it, he put the apt on market both for sale and for rent. He has been do this for years (we did not find this out until recently). I guess I can not do anything about this, am I right? By the way, I am in NY.