We have done good work in complex Magento, Prestashop projects. EXAMPLE 1 (Magento): http://busybody.com.sg - This is a eCommerce website to sale deals & coupons. It is a bit similar www.groupon.com - It is multi vendor (merchant). Vendor can post & manage their products and order. Vendor screen: http://www.globosoftware.net/images/portfolio/busybody-merchant.png - The site is allow vendor (merchant) to manage the sold & redeem deals by QR code: http://www.globosoftware.net/images/portfolio/busybody-qr-code-redeem.png - The site is also using custom Drop Shipping service (Ezy2Ship). We have to create custom code to migration Ezy2Ship API with Magento. EXAMPLE 2 (Prestashop): http://www.partecipazionieleganti.it - The site allow user design personal card & calendar. User can add text, change font, change color, add photo... Each steps, extra price will be added to cart. EXAMPLE 3 (Prestashop): http://fastballoons.com - The site allow user to design their balloon & pen. User can add text, image, change font, add note to admin... There are a lot more complex project that we have done previously. You can see in our portfolio. 5.0 rating, high recommendation from our clients, and a high percentage of them returns for more projects, all these tell about our quality of service.