If you wanted to sell your slot car collection - would you sell it one at a time, in batches, or all together?
I think you'd get the most money going a piece at a time.

--Fordcowboy

Wow you scared me. I thought for a second you were letting go of some of your cars.

Now to your question:

If "I" sold my cars it would be due to financial difficulty. So to get the most I would list them on E bay one at a time with discounts for purchaseing multiple auctions.

If my family sells my collection after I'm gone. Sell them all at once, but then again I don't really care how much they get just as long as they go to someone that will love them like I did.

To maximize the money, I would piece them out one at a time.

break up most of them, you will always make more selling individually, but I myself would probably sell in small lots, 4 to 5 cars at a time (really just to save listing time)