Craigslist 440. Whats it worth?

Wow, that's amazing how much different prices can be from different areas. I am picking up a 440 block, with several parts that has been tanked and magged for $75. I see alot of complete 440's going from $150 to up as high as $650 or so. The higher priced ones are on for months being relisted several times. I know there is a '67 383 with 727 transmission out of like a fury or coronet I can't remember which but the have been listing it for over a year off and on for like $350 once then $500 the next, then down again (not sure of why) but it's the same ad otherwise and it never sells. I remember seeing the ad the first time when I bought the compete 400 for $250 for our duster over a year ago and it came complete with trans. I bought a complete '70 383 for $50 a few months ago, and $150 for the trans with it.