To me, saving $40-$60 and have the risk of a flash that has been used extensively just doesn't make sense. Unless I am getting from somemone I know.. otherwise, I would still prefer to get it brand new. Shoud the flash breakdown, I dun think the saving is even enough to cover......... :dunno:
I think manufacturers construct their products with a mind to keep it lasting for a pretty long while. Still, as we've grown to notice, electronics do not tend to be horribly durable, perhaps due to the humidity here, the carelessness of users or otherwise...
With this in mind, I'd say that most users do not come close to the expected life of the product (shutter count for dSLR, miles clocked for cars, and, apparently, bulb life for flash, although this is a new concept for me... I don't really know how it is measured)
Thus, IMHO, buyers should discount the 2nd-hand product based on the condition of the flash and the perceived treatment it received from its original user. Ha... How much to discount is entirely up to the buyer himself.