UK
Full time - Minimum wage
Month : £1094 ($1688.69)
Week : £273.50 ($422.17)
Full time - National median
Month : £1733 ($2675.05)
Week : £433.25 ($668.76)
Full time - Household net median
Month : £3212.25 ($4958.41)
Week : £803.06 ($1239.60)
US
Poverty (Single)
Month : $976.67
Week : $244.17
Poverty (Family)
Month : $1957.67
Week : $489.42
Full time - Minimum wage
Month : $1256.67
Week : $314.17
Full time - National average
Month : $4251.42
Week : $1062.85
Full time - Household net median (Median of all races)
Month : $4762.92
Week : $1190.73
Full time - Household net median (Asian)
Month : $6395.58
Week : $1598.90
Full time - Household net median (White)
Month : $5443.08
Week : $1360.77
Full time - Household net median (Black)
Month : $3390.42
Week : $847.60
Japan
Full time - National average
Month : $2088.83
Week : $522.21
Full time - Household net median
Month : $3680.05
Week : $920.01
Poverty rates as of 2012
UK : 16.2%
US : 17.3%
JP : 15.7%
Sources:
http://www.dol.gov/dol/topic/wages/minimumwage.htm
http://www.dol.gov/whd/minwage/america.htm
http://data.worldbank.org/indicator/NY.GDP.PCAP.CD
http://money.cnn.com/2013/09/17/news/economy/poverty-income/
http://www.oecdbetterlifeindex.org/countries/japan/
http://www.stat.go.jp/english/data/kakei/
For a kid living at home with parents in US,UK or Japan, providing they actually work, even at minumum wage it would only take 3 1/2 weeks worth of pay to afford all three systems, 4 if said person was considered "in poverty", though chances are people in that situation aren't going to waste money buying ANY consoles.
Even if said kid is paying approximately half his earnings in rent/payments to parents, Within two months all three systems could be bought, along with games.
For everyone else, living alone/with partners/families, providing you are not living above your means (i.e. barely paying the rent because you wanted to live in a nicer area than you could afford, or because you just had to get that new phone on contract, or new car, etc, then saving $1000 should take less than 2 months easilly.
It's all about budgeting and money management, if you are bleeding money from multiple small payments each month, paying off credit card charges, loans and subscription charges and can barely get by, then you shouldn't be buying consoles to begin with, you should be focusing on paying off the debt.
If not in debt, then the only feasible reasons why "all three" is not an option financially, is if you are, a) piss poor at money management, or b) in poverty.
"Not an option preferentially" is an entirely different thing all together.
If you're that hard up that saving $1000 within a few weeks or months looks like an impossible mountain to climb, I strongly suggest you shut down your PC, call your internet provider and cancel your subscription, then consider selling the pc/laptop/phone/tablet you are using because these are clearly luxuries you cannot afford, and you are living beyond your means.
If that $1000 is impossible to climb because you have no employment, chances are you would be using your time better looking for employment rather than wasting it on a gaming forum.
Sure, it sounds harsh, but it's the truth. People in general are terrible with money management.