$400 is a fair price. If you enjoy restoring old bikes, have the time for the hobbie and are a pretty good mechanic then go ahead and pick them up. Expect to spend $200 to $400 on each one to get them back in decent shape. Used ebay parts would be the way to go and it may be cheaper to rebuild the heads than I think. I wouldn't pay more than $400 if both are missing the top end hardware.