Actually there are a few sources if you search online. I'm not affiliated to this guy, but I think he's one of the best sources out there:
singapore.gumtree.sg/c-Stuff-for-Sale-Other-CMFAS-Mock-Papers-M1A-M1B-M5-M6-M6A-M8-M8A-M9-M9A-HI-W0QQAdIdZ240236503