Finding used go stones

My landlord has an old set of Go stones, some of which are a bit damaged and chipped and he's missing a few of each colour. Is there anywhere in Japan I could get him some replacements? He's not looking for a complete set, just "spares" of the right size. They're quite thin shell-and-slate stones, not expensive but nice to play with, he tells me.

I'm travelling over to Japan in mid-May and I will have a JR pass so I can get around Tokyo, Kansai and other places as needed. I will have some damaged spare stones with me as samples to compare if needed.

not used ones but new ones,though,

http://www.kurokigoishi.co.jp/english/index.html

I see used go sets fairly often at the 2nd hand shops and flea markets. Its pretty hit or miss though, so not really sure where to find them while travelling.

FMI, they sell 10-pieces-sets to replenish lacks or chipped ones.

http://www.kurokigoishi.co.jp/onlineshop/replenishment/index.html

Thanks for the Kurokigoishi links but the stones I'm after are only 5.3mm thick, much thinner than the smallest stones they sell (30号, about 8mm thick). These are what I call "oyaji" stones, very old but not high quality even though they are slate and shell.