Hi bhairavp,
I happened to be in Japan for some months and was also checking second hand prices. What I experienced is that in most cases the lenses are not cheaper than in europe (where I am living).
Strangly a new lens is sometimes cheaper (compare with amazon.co.jp).
If you see an suspicous low price you should let a Japanese check the description, if you are not able to read it yourself.
In most cases there is a small piece of paper next to the lens stating if there is dust inside the lens, if there is a lens cap and so on. In bigger stores they also have categories for the condition of the lens.
I believe especially in Japan there are photonerds everywhere and its not like in europe where you can easily spot a great deal since everybody is checking the small second hand store nearby. Also there are some big stores specialised in selling used camera stuff which will also buy from the smaller shops.
To compare prices you can check this shop:
Map Camera (
http://www.mapcamera.com):
It is a bit more professional and therefore maybe expensive, but they have nearly everything. Bought a Sigma EF-530 DG-ST for 7,800 yen and an Pentax D-BG2 battery grip for 5,800 yen there in pretty much like new condition. They have two main shops near Shinjuku Station.
For cheaper deals you can try Sofmap (
http://www.sofmap.com/):
But their pentax stuff is limited since they sell everything not only cameras.
For both these shops be sure to check the conidtion of the lens in the description! Especially if too cheap to be true. Sometimes one gets easily blinded by low prices
.
Also I would recommend not to buy anything from the big electronic stores like Yodobashi Camera or Big Camera, as they are totally overpriced. Compare the prices to amazon.co.jp and see for yourself. Maybe if you have a point card and buy anything else but even then...
In general I would say in Japan its a bit more pricey but you can be sure to get a second hand lens/camera as advertised or better. For ebay its mostly the other way around
.
A new DA70mm 2.4 limited costs ¥37,800 at mapcamera.com/amazon.co.jp (Yodobashi.com ¥43,100). So I guess the lens you saw is in good condition since the discount is not so huge.
PS: If you are in Tokyo be sure to checkout meiji jingu in Harajuku. If you are looking for a great night view checkout Mori Tower rooftop in roppongi midtown around 19:00 o`clock. Before they switch off the orange light of tokyo tower
. Study your camera on the railings for a long exposure, I think there are no tripods allowed there.