well, even in Yahoo Japan prices go crazy sometimes
one day I buy lot of 3 medals for 10000 Yen ... another day each one goes to buyers for at least 6000 yen each. Why? Because it is an auction.
As of Kite 6th class ... I see it all the time at yahoo auction ... sometimes price go crazy (in my perception) and it sells at 35000 ... sometimes huge lot shows up which includes Kite 6th, Rising sun 6th, Sacred Treasure 5th for example and it sells for 30000 yen. Someone who needs only Kite and doesn't want to bother himself with reselling items - just buys Kite and doesn't care that he "overpaid" another one might go for it ...
There are collectors for whom the value of particular order is different. For me it might worth no more than $200, but for someone to complete his collection it might worth $1000. As well, do not forget that not everybody can buy via ebay (blame computer literacy, access to ebay, whatever) ... and they buy from the local dealers who in turn buy from ebay ... I've seen those dealers web-sites and sometimes I sell directly to them ( Europe). Then I see what price they charge at their web sites - it is far beyond ebays price - and it sells out, because they have a particular order from customer who is ready to pay $1000 for lets say Kite 6th, so buying it for $600 and reselling for $1000 not a bad deal for a middleman.
Experienced buyers from ebay prefer to contact sellers directly and ask for particular awards for preset price, if both agree on terms it goes without anyone noticing it. I sell sometimes on ebay and have this kind of customers
Saying this, there is no right price for everybody ... and there is no right price in any particular time ... everything determined by supply/demand and willingness of buyer to accept it ... demand for Japanese awards went up for sure ... supply? it mostly the same it was because here are collectors in Japan as well .