You should be able too. Just talk to Tom Nook.
Pay or sell at least 240,000 bells worth of items.
If you put $25000 under your mattress in 1900, today it would be worth $25000
$25000
25000
$180,250
you have to buy/sell (does not matter) 240,000 bells worth of stuff AND have a friend buy something from your shop before he upgrades to Nookington's
15,000 bells
round about 800 bells
Not much!
25000 British Pound equals 32355.25 US Dollar
A Salmon is worth 700 bells. A king salmon is worth 1,800 bells.
2,000