The value of a finished battery pack is about $20 / lb. Truck transport across the US costs about $0.35 / lb. So indeed, proximity to installation locations makes less than 2% difference.
Reno is ~235 miles from the Fremont factory, or about 4 hours.
The gigaplant is going to be a critical part of Tesla's supply chain, and distance is critical. Better to have your main component within a short drive, and let cells/packs destined for others make the long slog via rail or ship.
