I live in Park Slope and drive a reverse commute to Staten Island. Park Slope prices, especially with regards to buying, are almost at par with Manhattan. The economic downturn saw some softening of Manhattan real estate, but Park Slope has been pretty stable in comparison (20-25% drop in RE versus 10-15% respectively for 1 BR and studios). Rentals between the LE Side and Park Slope are within a few hundred bucks (Park Slope 1BR 1600-2k). The demographics inhabiting the two areas are completely different. Park Slope is filled with young professional families. Manhattan will likely attract a post-college demographic and cater to those individuals. Boerem Hill, Coble Hill, and Carroll Gardens will all be priced around the Slope.
FWIW, Red Hook is rapidly gentrifying. I love the Fairway in RH. Bay Ridge is too damn far to commute. Astoria might be worth investigating though its grittier than the affluenct parts of Brooklyn and still priced according to its close proximity to Midtown. (1BR 1400-1700)
Hoboken might be a better alternative if you work in Lower Manhattan. The bar and restaurant scene caters to single people.