The Sims starter home under $20.000 designed for a family up to 4 sims, modeled based on shotgun houses, originating from New Orleans and common in south states from 1830s to 1920s, single-story, 3-4 meters wide and 20+ meters long, having 3-5 rooms in row, entrances in the endmost rooms and no hallways.
In The Sims 2 house I cheated a little and made entrance in the second room, for purpose of layout optimization.
Lot size: 1×2.
Lot facing: North.
House price: $20.000 furnished, $? unfurnished.
House size: 6×14.
Floor area: 88 squares.
Expansions required: none, base game only.
PS: I do not know how to create such small lots like 1×2. I downloaded them from ModTheSims.info (Mini residential lots by MaryLou).