Always built houses THEN move family in them. NEVER move family to an empty lot then build the house, because only 80% of Build Mode costs are added to home value. The loss of money will be even bigger if you build, demolish and rebuild.
A way to have a even better furniture in less than 20K is to move a rich family in the house and play it for 5 days, as the Buy Mode items depreciate with 15% per day and reach terminal value of 40% in 5th day (unlike The Sims 1, items no longer depreciate at infinite), then kill all Sims, the house will be empty, for sale, but with used furniture.
Use cheapest items for tables and counters, as these things do not affect Sims mood.
My Best Starter Home include a computer, later I found that this is not necessary. Use computer to find a bigger variety of jobs for your Sims, then sell the computer and buy better beds.