A useful next step would be to post one anonymised example on the local board: general location, asking price, size, vacant or tenanted, condition, and the completed-price evidence you think is comparable. Members can then challenge the assumptions rather than recommend data in the abstract...
Ask for two itemised schedules: everything due to complete the purchase, and everything payable each year afterward. Also have each line marked buyer, seller or negotiable rather than assuming the label tells you who pays. For the condo itself, request the current recurring charges and ask...