For more design choices POD-Frenzy.com is perfect for POD Designs or Crafting Designs. Each has a license that will allow you to use them for commercial print on demand. Their crafting designs come in more file formats, so they can easily be used for cutting machines.
It is possible to buy the designs separately ($2.90 per design) or to subscribe to get access to all the designs and gain more exclusive advantages.
POD Frenzy also helps you set up other print-on-demand shops like Etsy, RedBubble, Teepublic, or Teespring stores. Aside from that they also help you set up your Shopify or Woocommerce store Lastly, based on their experience with dropshipping and print on demand, they can work with you to scale up through their consulting services.