Updated through Gaul & Byzantium pack.

Initial Upload
Standard Districts cost 100 production regardless of game progress.

Other district costs calculated from standard district cost using vanilla district base cost differences. Except Neighborhoods. That one was guesswork.

Unique Districts = 50 production.
Aqueducts = 66 production (Bath = 33 production)
Government Plaza = 55 production
Canals, Dams, and Neighborhoods = 150 production

Spaceport cost unchanged at 1,800 production.

Should effect modded standard and specialty districts appropriately, but this is untested.