I guess it might depend on the "what" and the condition.
For example, I've bought a Pentax Spotmatic & 50/1.4 on Yahoo Auctions for $1500 yen, listed as "junk status, no returns", that, upon receipt, look better than most of the "Excellent" stuff I get on Ebay. I've been able to pick up several Mamiya Universal Press 6x9 backs on said auction site for 3~4000 yen (they go for 70~80USD on Ebay). I purchased a WLF for my Pentax 67II on Yahoo for ~4,000 yen or so (much more expensive on Ebay). You can go get a Norita 66 on Yahoo for ~80,000 yen (1K USD), which go for 12~1300USD on Ebay. Etc.