The Japanese do collect US bikes but, good luck finding them and if you do, be prepared to pay double, in the least. They also restore em and they're anal about that, pure perfection or trashed!
They're also wasteful. That is, no yard sales and hardly, if at all, buyers of used items. In fact, they pay to haul off seriously good stuff. Junk men run routs daily, U pay.
I guess, some that stuff does land inside of junk shops because, there's a few if you're willing to hunt em down. Most people wouldn't be caught dead inside of one yet, that's probably why those are expensive too, a sale a week pays the rent. Probable the biggest used item market is bulletin boards where U.S. and oher temporary visitors resell their apartment stuff, furniture and household items. where those BB's are, is also the place to discover were other English speaking folks turn up to ask where some might be. They've a very tight immigration policy so, not many can stay beyond their visa. Selling their stuff, leaving, visiting India, Africa or other Asian parts until they can return and buy stuff again. .
regardless, you've got to get out of their cities or well off into side streets, junky looking side streets, if you can find junky their, to find old stuff that wont cost an arm, liver, kidney or leg for any kind of collectible items and I ain't talking bout USA junk but, any. . Antique stores? yeah, for-get-about it, that stuff is cheaper in the USA and or ebay. even new japan made stuff is cheaper in US retail stores than Japanese.
.