The price difference is from the facts that Omega came up with the watch design, R&D, the better more accurate movement licensing, the advertising so that people want this watch, quality control, water resistance, warranty, box, better straps, better quality materials, etc. The rep makers are piggybacking off this popularity without all these overheads.
You're forgetting movements like in the AP, the true GMT movements found in R**** and Om***, the new PAM in-house movement, the king of movements, El Primero, Pateks etc etc. There are quite a lot of quality movements out there