Keep it for NJ. Get crazy with local information, neighborhood data, community information. Become an
www.electronicAppraiser.com affiliate, provide AVM reports for FSBO's to find out what their house is worth.
Capitalize on how you can make the site more intimate because you are focusing on NJ, versus nationwide. The shore, NY City up North, Philly to the south.
Again, keep it local, because you'd be one of the 200 nationwide, FSBO sites out there.
Cool idea...consider About.com, freelance writers earning some chump change per month to write about a topic. Consider topics like entertainment, colleges/universities, community information. Solicit people to help write content on NJ, pertinent to your site.
Good Luck