Easy money...
	Gamecenter Achievements...
	Stock Up...

Enter the system's settings and change the date to one day ahead. Note: This can make wait times longer; stock everything before turning the date back.

Achievement	How to unlock
Amusements	Fully stock a Toy Store & Tech Store.
An Eye for Art	Fully stock an Optometrist & Art Studio.
Bar Fight	Fully stock a Pub & Martial Arts.
Bet the Pot	Fully stock a Casino & Pottery Studio.
Blockbuster	Fully stock a Cineplex & Video Rental.
Bookwork	Fully stock a Book Store & Plant Nursery.
Burger Bytes	Fully stock a Sky Burger & Cyber Cafe.
Cloud Topper	Build 100 floors.
Code Freeze	Fully stock a Software Studio & Smoothie Shop.
Cold Medicine	Fully stock a Frozen Yogurt & Pharmacy.
Cut an Album	Fully stock a Barber Shop & Recording Studio.
Dance Fever	Fully stock a Night Club & Doctors Office.
Decked Out	Fully stock a Mens Fashion & Hat Shop.
Designer Shoes	Fully stock a Graphic Design & Shoe Store.
Desserted	Fully stock a Cake Studio & Scoops.
Dirty Laundry	Fully stock a Private Eye & Laundromat.
Fashionista	Fully stock a Fashion Studio & Womens Studio.
Fat Quarter	Fully stock a Health Club & Fabric Shop.
Field Trip	Fully stock a Tutoring Center & Museum.
First Quarter	Build 25 floors.
Fish Tacos	Fully stock an Aquarium & Mexican Food.
Five Oh	Build 50 floors.
Fortune Cookie	Fully stock a Fortune Teller & Asian Cuisine.
Funny Money	Fully stock a Comedy Club & Bank.
Green Screen	Fully stock a Vegan Food & Film Studio.
iGlass	Fully stock a Mapple Store & Glass Studio.
Joystick Junkie	Fully stock a Game Studio & Game Store.
Keep Rollin	Fully stock a Bike Shop & Bowling Alley.
Musical Chairs	Fully stock a Music Store & Furniture Store.
Nerd Alert	Fully stock a Comic Store & Arcade.
Nice Shot	Fully stock a Paintball & Racquetball.
Oakinawa	Fully stock a Wood Shop & Sushi Bar.
Pizza Roll	Fully stock a Pizza Place & Bakery.
Please Be Seated	Fully stock a Theater & Wedding Singer.
Printer Ink	Fully Stock a Print & Ship & Tattoo Parlor.
R&R	Fully stock a Day Spa & Travel Agency.
Rags to Riches	Fully stock a Diner & Fancy Cuisine.
Say Cheese!	Fully stock a Dentists Office & Photo Studio.
Something's Brewing	Fully stock a Coffee House & Soda Brewery.
Spike in Sales	Fully stock a Volleyball Club & Ad Agency.
Stellar Record	Fully stock a Planetarium & Record Shop.
Subpar	Fully stock a Sub Shop & Mini Golf.
Tea Square	Fully stock a Tea House & Architect Office.
Tiny City	Have 100 residents.
Tiny Town	Have 50 residents.
Tiny Village	Have 15 residents.
Triskaidekaphobia	Build 13 floors.

If you enter the system's settings and change the date to one day ahead you will make the wait times longer which will allow you to stock everything. When you have stocked up just change the date back.