[McMurphy]

I think the point Arbys and a few others mentioned is critical here. Sell off the worst of them first, saving your best for last.
Reason for this is two fold.
The damand and disposable income to buy them with may both increase with the span of time this is certain to take, (guess no less than 5 years for that many) and you will get a better price when you need it most for the cars in the best condition.
Second, if you save the worst for last, then the temptation to scrap them may win over and that would be a criminal waste and shame.

And also as stated above, just my worth...
Good Luck and godbless for keeping that many for so long from the crusher !!!