Kind of hitting on an old topic here, but here is my take.
Back in about 86 or so, the American muscle car craze hit some foriegn countries (Japan especially). Word got out about the outragious prices these guys were willing to pay for an original, or highly restored example of an American car. Though I dont believe all that many were actually sold, like any culture (our BSA 10 and 7s included) speculation soon took hold.
I used to subscribe to a magazine called Hemmings Motor News, and in a matter of just a few months it seamed, you could watch the price of a nice '69 Mach 1 (mustang) go from $13,000 to mid fiftys for the exact same car. This lead to even more speculation, and more buyers willing to pay that in hopes of re-selling the vehicle for even more in a matter of a few months (or weeks). The prices just kept going up and up and up.
The more "original" a car was, the more its presumed value. Lordy, if you had a tank sticker, and found a build sheet under the rear seat and everything matched up, the sky was the limit!
Now enter Mr. Shifty. He was a willy one, and not only had the ability to forge tank stickers, build sheets, and complete history of the vehicle- but also the ability to research and re-stamp parts numbers. This brought about the need to have a check done on all stampings. Now we are not talking back yard restamp here, but work of professionals. The only way to tell if a block or tranny was restamped was to look at the grain of the metal under the new stamp- there would be a shadow of the old "bruise" from the original stamp- and this took very special equipment and cost a lot of money- but people who could afford it paid for it. Many who couldnt, got burned badly.
Trying to buy or sell a car became a matter for the bean counters, crawling all over looking at everything from the ash tray to the gears for the window winders to the brackets for the front bumber. If there were a lot of correct numbers, you paid or recieved a lot of "beans".
It seams everything in the late 80s followed this theme, it had to be spot on correct or just wasnt worth paying for.
Then, in about 89 0r maybe 90, reality hit. The muscle car culture is large in comparison to ours, but the same rules apply. We enjoy the bikes, enjoy working on them, collecting bits and pieces- its a useful hobby. But how many of us would pay $80,000 dollars for a restored a10 flash? And even still, how many of us would ever ride that bike? Not many I would think.
The prices crashed as fast as they went up, people came to their senses and were no longer willing to pay three times more for one collector car then they did for their home.
The only ones left crying were the guys who paid $90,000 for that "everyday" '69 Mach 1 hoping to make a killing, and in a few months time couldnt get $20,000 for it. I think that was the death ring for the bean counter era, and hopefully besides a few VERY special cars and bikes, we never see anything like it again.
Lee