New York State Transfer Tax is $4 per thousand, i.e. Sales Price $300,000 then Seller Pays NYS $1,200
Seller also pays .05cents per Share for Stock Transer Tax, i.e. 500 Shares then Seller Pays $25
Normally the Seller Pays Co-op Flip Tax (formula may be based on various methods i.e. Sales Price, #Shares, Size of Unit or Seller's Profit from Purchase, etc.).
Some buildings may have a very expensive Buyer's Application Fee in lieu of charging Flip Taxes.
There are potentially Move-in and/or Move-out Fees and/or Security Deposits.
Co-ops may also charge an Application Fee, Credit Check Fee & Management Co Processing Fee.
Plus fee for either Management Co or Co-op Attorney for attending the Closing.
Best to obtain all details before making an Offer to Purchase.
Certainly there are traditional fees that have been assigned to buyers and sellers depending upon region and specific location.
It is important to understand that these guidelines and traditions are still enforced via contract.
Write the contract in whatever way best suits your situation. The offer will then be negotiated in a manner that will ultimately be agreeable to all parties.
Very common in the NY area for buyer to pay those fees.
With a good agent and a good attorney it is sometimes possible to negotiate them, so the seller would pay, all depends on the co-op.