I am not well versed in the second-hand trading. Is it usual for items to change hands so often that they can benefit from having a ... diary?
Well I bought myself some second hand lenses so far, which would be much more expensive if you buy them new. For this for example it is often written/said how many people have owned them so far, when it was bought, maybe if there was a repair needed etc. I think at this point Soma could help here because you could see if the written/said is true or not. Maybe someone wants to lie because the lens wasn't bought new from him but two persons before or something.
But I am wondering how you want to manage this with items you can't track through a serial number or something like that.