[Suicide Junkie]

GK: The answer is also partly in the title of the thread.

You build a cheap design that can be completed in 1 turn.

You then retrofit it to a design 50% more expensive.
You retrofit THAT to a design 50% more expensive than the Last.
Repeat as nessesary.
By the time you've doen it 10 times, you can be left with a ship 50x more expensive that the original hull.
Turn 2, you repair the components, and you now have 1 super-expensive ship completed way ahead of schedule and many times OVERbudget. Since you pay for both putting components in and taking them out, you've spent way more money than just building the thing straight up would have.

If you wanted to build a sphereworld in two turns using this method, it would cost somthing like 6 million resources instead of 300,000.