You could save up for who knows how many years *gets out calculator*
So I live in Australia so naturally my calculations are I Australian dollars :3
The average weekly wage of an Australian is: $6302
7 days in a week means that per day wage is: $900.28571428571428571428571428571
365.25 days in a year (that is counting the extra day each leap year as an extra quarter day per year)
That comes to a yearly total of: $328829.35714285714285714285714286
NOTE: I am not rounding this so that rounding errors when I calculate the huge price is as minimal as possible.
We have established the cost of a death star in American dollars is $15,602,022,489,829,821,422,840,226.94
With current exchange rates to Australian dollars being 1 U.S. dollar = 0.974468914 Australian dollars (according to www.ozforex.com.au the first Google result for exchange rates) that makes the cost in Australian dollars: $15,203,685,911,868,042,126,729,050.741735
If the average yearly wage for an Australian is: $328829.35714285714285714285714286
And the total cost of a death star in Australian dollars is: $15,203,685,911,868,042,126,729,050.741735
The total time it would take to save up the money by yourself to even afford a death star is: 46,235,792,460,777,548,271.173804733782 YEARS!
In Layman's term, a really long time OR 46.356 quadrillion years...rounded by a few billion.
And just just in case anyone wants to know how long the 0.173804733782 at the end of that is, it equates to: 63.4821790138755 days
To whittle that time even further down and closer to exact the numbers after the decimal equate to: 9 weeks (63 days), 11 hours, 34 minutes, 20 seconds, 269 milliseconds, 988 microseconds, 432 nano seconds
Realistically the time you work is measured in hours or at smallest, lots of 15 minutes (usually), so for time you have to work sake lets call that 9 weeks 12 hours
So in closing, to afford a death star in Australia (if inflation stops completely, I'm too lazy to work inflation into the time it would cost cost of materials getting cheaper would also be a huge factor over such a long time) it would take the average Australian:
46,235,792,460,777,548,271 years, 9 weeks, 11 hours, 34 minutes, 20 seconds, 269 milliseconds, 988 microseconds, 432 nano seconds (assuming work in that far a future if a lot more accurate than hour blocks)
Or you could spend a lot less time and collect the Dragon balls and wish for two of them, then sell one for scrap and be infinitely wealthy so your Great-Great-Great-Great-Great-Great-Great-Great-Great-Great-Great-Great-Great-Great-Great-Great-Grandchildren will NEVER have to work :3