• Spreadshirt – You can customize your shirt using sophisticated and user-friendly online designer. You can upload your own design or use their vast collection of designs. You can open a ‘spreadshop’ (for free) where you upload a design, make a shirt, and set the commission so you earn the profits.
  Go to Spreadshirt
• Com Boutique – They call their custom t-shirt ordering process the “T-Shirt Minute. The have the best brands and models (Fruit of the Loom, Hanes, B&C). They have a “Hot Stuff” page that features various products that people created. It allows you view, purchase, rate and comment on each shirt. You can sell your design too.
  Deal: Use discount code FREESHIP and get Free Shipping at Com Boutique
  
• Customized Girl – Customized Girl is an online retailer of customizable clothing that specializes in personalized clothing targeted mostly to fashion-knowledgeable, fun, young to middle-aged women. However they also have clothing for men, children/kids and pets. How cool is that? Customers can select any clothing item on the site from underwear, to yoga pants, to shirts. Customers can then, through the use on an interactive design tool, add text and clipart to their products in real-time. They also have the ability to save their designs in the “community gallery” for purchase at a later date or purchase by someone else.
  Deal: Use promo code POSH and get 15% discount
• Shirtcity – Designing a custom shirt at this site is very easy. You can actually design personalized shirts, underwear, caps, lanyards, mugs, and teddy bears. They also offer a special “Shirt of the Week”. For that week, this design is offered with $5.00 discount on all products. Opening a Shirtcity Shop was even easier. Just pick your shop name, customize it a little bit and begin designing shirts to sell. It took us less than fifteen minutes to sign up for an account and have things up for sale. You can earn extra money if you are the cream of the crop and be a winner of their monthly t-shirt design contest.
  Go to Shirtcity
• Shopster – If don’t want to use custom design but you want to sell a brand name designer clothings, try Shopster. They have fully customizable storefront, marketing and sales tools and they also have dropship product source inventory. You do not have to go through the lengthy process to get a web host, find dropshipper, setup website, build shopping cart, and then  sell a product.
  Go to Shopster

For more info on starting a t-shirt business, go to t-shirtbusiness.com