collecting 40's50's60's glass containers

Hi Been looking for NG"S relating to vintage glass refrigerator containers such as Pyrex, Fire King, Ferderals but not having any luck. Been lurking on e-bay but I couldn't tell you vintage from reproductions which many dealers I hear are making big $$$$$$ ripping people off. Does any one know of group online that I can learn markings to spot fakes and values etc.? TIA