Just looking briefly at the listing information, this looks to be a duplex unit on multiple floors. The more square footage a unit owner has in any condominium project, then the higher the percentage of the common area expenses that unit will have to cover. Your percentage of the building expenses is based primarily (although not exclusively) on the amount of the total space/footprint that the individual unit affects/is responsible for. At 2300 square feet, this amount for an assessment does not sound too remarkably out of line. As Jeff states below, you will have the opportunity to review the the condominium association's documents and meeting minutes and financial documents. Good luck to you.
Broker Associate, Sudler Sotheby's International Realty
good luck and be sure to use a buyer agent with experience in short sales!