To echo CommissarMoody, that is a great idea. I have actually completed the templates for the full building but it is quite large and would be extremely pricey to make (probably around $200).
A lot of that price though is based on all four walls having equal detailing.
What I did with the art deco skyscraper I made (there is a pic attached) is that I did two walls complete with detailing and then made the other two ruined so that you could get your hands inside to move things around.
But this is a requirement of 40k where movement within buildings is needed. Do a lot of the games you play not need the models to move inside?
I'd be building them with removable roof and removable interior floors (if needed), which is how I do all my buildings. For multi-storey buildings with a fancy front, you can build the higher floors as three-walled "trays" that snug up to the intact multi-storey front facade.
As a minimal mostly-DIY kit, how about just the fancy facade as a kit, with other walls/roof/floors/etc to be provided by the buyer? One wall of fancy detailing would probably be about the same as two of your corners, in terms of materials and cutter time, I think?