try craigslist socomtyson, thats where i found mine, here are a few links in the NYC area:
http://newyork.craigslist.org/wch/car/316817273.html
http://newyork.craigslist.org/que/car/316012715.html
http://newyork.craigslist.org/que/car/319089385.html
i don't know what your definition of "decent" is but you might have to spend 3500 - 4500 for something in better shape such as these below:
http://newyork.craigslist.org/lgi/car/318427086.html
http://albany.craigslist.org/car/294044115.html
http://albany.craigslist.org/car/309145181.html
http://buffalo.craigslist.org/car/313234860.html
I got lucky when i found mine because the guy was actually 5 min from my house so i got to inspect it thoroughly and I got to bargain with him. I'm no Legend expert but for 5000 - 6500 you'll get a pristine looking Legend inside & out. Hope these help or at least give you an idea of what you're getting for your money.