Answer: six items, and two of them eliminate most of the price gap between quotes.
- Certification status of the exact model.
- Conductor material and gauge (AWG).
- Shielding construction (foil plus braid).
- Distance limit at the target bandwidth (copper vs AOC).
- Factory traceability (ISO 9001, incoming inspection, lot trace).
- Batch-to-batch consistency between sample lot and mass production.
A quote that cannot answer items 1 and 6 in writing is usually cheap because certification and lot testing are missing.