One thing I've found is that (in general) Fotga=Neewer so keep that in mind when shopping.
Also, in general, the DP3000 line is plastic and the DP500 line is metal (for any part that can be plastic like the clamp thumb screws/knobs). That said my rig is mostly Fotga or other off brand that was CHEAP! Only expensive thing was the D|Focus cage for my GH2, and that is so out of fashion that most people are practically giving things away.
Also, in general, the DP3000 line is plastic and the DP500 line is metal (for any part that can be plastic like the clamp thumb screws/knobs). That said my rig is mostly Fotga or other off brand that was CHEAP! Only expensive thing was the D|Focus cage for my GH2, and that is so out of fashion that most people are practically giving things away.