Buying a home is one of the biggest and most important decisions you will make. It is impossible for me to tell you if the price is high, unless you can tell me which buiding you are thinking about purchasing in. I looked around but most condo/coop in Park Slope varies in price. I would suggest that you work with a real estate agent, we are usually effective in negotiating the price for buyers. There is no cost to you if you have an agent represent you. Condo's vary in prices from one building to next primarily because of amenities such as parking, laundry, gyn, doorman, pool, maintainence, age of the building, tax abatements, etc. You should decide what amount works for you and negotiate the price. The asking price is not set in stone.
Good luck to you. Please do not hesitate to contact me should you have any additional questions. I would be happy to assist you in securing a home for yourself.
Real Estate Agent