Yes, an in addition to the buy you get for buying a collection, there are the occasional "surprises" one gets.
I recently bought a Swiss collection, in a stock book, for 480 that drew no attention on
ebay. It was a treasure worth far far more and saving me a ton had I bought things either individually or in smaller lots.
-Larry
(My problem now is how to fill my holes. I don't what the massive duplication you'd get with a collection and individual purchases are just too expensive.)