This is the best possible starter home, under $20.000 designed for a family up to 4 sims. The 1×2 lot costs only $300 (the 1×1 lot costs $-400 but is too small). The empty home costs $5469, so $14.500 remained for furnishing. For the non-functional items (counters, table, windows, floors, wall paint) I used the cheapest items to save money for better furniture. Made in 2011 in the same time with Tiny House I having same ground footprint.
Even better 2012 version: removed not-so-necessary computer, changed the 2-sided roof to a 4-sided roof to eliminate attic walls and save money. Beds and toilets replaced with better items, added some lights (I have noticed drop of environment score during night if the room is dark).
Lot size: 1×2.
Lot facing: South.
House price: $19.989.
House size: 6×14.
Floor area: 84 squares.
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).