Most kits do include Castings, especially those on the 3mm shop, I think the only ones that have none or are limited in what they do have are the Worsley Works and Bill Bedford ones, but both of those supply etchings in multiple scales and are very much a case of scratch-aid kits.
All the Finney and Smith, 3mm Society and most, if not all, of the 3SMR kits include castings.