If you check the other cheats on other websites you will be able to see that you need to
do the following:
1: Spend 240,000 bells at Tom Nook's previous shop.
2: Ask a friend to visit your town and by an item.

By noe Tom Nook should have told you/posted on the bullentin board that he will be
remodeling his shop.

I hope my tip helped you.

To get Tom Nook to expand into Nookington's, you must spend 240,000 bells and have a
friend shop at the store. This shop has an automatic door. In Animal Crossing: City Folk,
you do not need a friend to shop at Nookway, and you only need to pay 150,000 bells for
Nook to upgrade to Nookington's.
It also has a hair salon, if you want a specific style, Google it.
Hope I helped =D

u have to have nook n go spend 240,000 at it then get a friend to spend 250 there

your not doing anything wrong.it takes a long time,so once you get everything you
want,never rebuild ur town.then it will be harder to get everything back,beleve me its
happened to me before.

you need to get the gold status over at nook's and poof! the day after he upgraded nook
way to nooking tons