Looking for sets to use as components of a 1930s - 1940s European city
What about the 75930 Indoraptor Rampage for an almost timeless mansion? Without the raptors it is not too expensive. 

The 10228 Haunted house could provide a good basis for a rebrick of a nice mansion on the hill just outside of your city. However, this one is ALWAYS expensive, as you probably know. 

For many nice little ideas for everyday items and a MOC city, check out LionBricks' Youtube channel.