I need a haircut; how do I get access to Shampoodles in this game? Her shop is greyed out and I don't like my haircut. Is it still part of Nooks' or what?
Unlocking Shampoodles is a twofold process: first you need to unlock Kicks (the shoe shop), by spending 8,000 bells in the Able Sisters' store. Then after Kicks is open, you must wait at least 7 days and spend at least 7,000 bells at Kicks and or the Able Sisters' shop and then Shampoodles will be constructed.
To unlock the store, the player must spend 10,000 Bells in Able Sisters or Kicks and 10 days must pass after Kicks opens. It takes 3 days to open. Also, to wear a Mii mask, players can choose the "makeup" option when Harriet prompts it.
So you have to spend 10,00 Bells at the able shop and kicks and 10 days must pass after his(kicks) shop opens.
According to Game FAQS
After you spend at least 10,000 bells between Kicks or the Able Sisters and 7 days after Kicks (The shoe store) is opened Shampoodle will begin construction.
After those requirements are met it is just a matter of when it happens.
To unlock Shampoodle's, you first have to unlock Kicks. To do that, you have to spend at least 8000 bells in the Able Sisters' shop. Kicks will open if it has been at least ten days since your town was created. Then, spend 10,000 bells in Able Sisters' or Kicks. After Kicks has been open for at least ten days, Shampoodle's will unlock and open on the second story of the Able Sisters' building.