Most auto parts stores sell remanufactured units at a reasonable price with a core trade-in. The previous poster has the price about right - if you hand them a core when you pick it up. It'll be more without the core, but you get your money back when you provide them with your old crankshaft as a core after you remove it.
I got mine special-ordered from O'Reilly's Auto Parts in about a day. Be sure to shop around! You might find a good deal!