At least for a Star Wars Collector. Over at the rebelscum forums a discussion is going on entitled Ancient History which is showcasing some of the great finds over the years. A lot of them are finds from Kenner Employees that were contacted and had a lot of stuff that was used in the preproduction process of the toys.
Recently someone mentioned the find known as the Dogatuna find. The story goes that this person basically bought loads of old Star Wars toys on clearance and put them in a trunk in the attic. His family thought he was absolutely crazy for doing this at the time. As time passed he eventually forgot about the toys. Then one day his Grandma was cleaning out the attic and came upon the chest full of Star Wars figures. She asked him what he wanted to do with them. He put a few on ebay for insanely cheap prices and they sold very quickly. I believe after that he sought out some research into exactly what he had and another collector stepped in to help him with the values. After that the pieces sold closer to market value.
The amazing thing is a lot of the figures made during the 1983-85 time frame have had the bubble that contains the figure turn yellow.
Many of the figures he had were still clear as the day they were bought. Also, a lot of the figures he had were from the Power of the Force series. These were the last figures made which also included a collectors coin. When these figures came out the majority of kids had moved on to other toys, so they sat on the shelves forever and were clearanced for insanely cheap prices. Because no one wanted them back then, they are now the most desired figures. Even out of the package they are the most expensive figures.
Here are a few pictures that I saved a few years ago after the find. I wish I could have picked up at least one at the time, but I did not have the funds to do so. To give some idea of value just those Luke Stormtrooper figures are worth around $300 a piece today when back in 1985 they would have just been a few dollars.