Like everything, it's random. There's no "set place" for farming Req. 8 items, at least not to my knowledge. Regarding having to be in Hard Mode, it sure would help, I'm sure.
Actually, some people I've talked to see to think HM is worse for finding req 8s. Keep in mind, req 8s existed years before HM was introduced. But yes, it is VERY much random. There is no set place.
