In order for you tobuild your own gazebo canopy it is best to decide what type of wood and materials that you would like to use. You should first start out with a sketch of how you want your canopy to look like. You can buy wood and tools at your local hardware or lumber store.
If you are good at construction, then building you own outdoor gazebo is an option. It will be better and probably cheaper to just have someone build it for you.
A canopy or Gazebo
Make sure to take proper measurements and purchase highest quality canopy at local home store then double tie canopy to gazebo.
form_title= How to Build a Gazebo form_header= Build a beautiful gazebo with help from the experts. What are your desired gazebo dimensions?*= _  What color would you like to paint the gazebo?*= _  When does the gazebo need to be completed?*= _ 
You could use sail cloth or canvas to make a gazebo canopy. Check your garden stores or big box stores for replacements.
A gazebo is a pavillion structure. A gazebo is typically octagonal. A "normal" gazebo typically has a roof that is hard and more difficult to replace. While a canopy gazebo has a softer top that can usually be replaced more easily as it is cloth material.
A good website is gazebo-plans.com. This website is a great resource if you plan to build your own gazebo as they have pointers and plans for different sizes and shapes.
buy a new gazebo cuz we are all screwed ! they do not want us to replace canopy only !
At a shop, is usually the best place to buy them.
Universal Concepts, Kilcoole, Wicklow
A gazebo with canopy can cost you anywhere around $100 to $300, depending upon the size, model and material of the gazebo and canopy. You may like to try any of these sites to have an idea about the gazebo-http://www.amazon.com/Outdoor-Tiverton-Gazebo-Replacement-Canopy/dp/B002RXIJI8; http://www.drugstore.com/products/prod.asp?pid=217573&catid=137143&aid=337953&aparam=southern_patio_sales_10_&CAWELAID=339141779; http://www.lowes.com/pd_57295-19407-C-1210GZN_?PL=1&productId=3152361&cm_mmc=search_gps-_-gps-_-gps-_-Garden%20Treasures%2010'%20x%2012'%20Gazebo%20Replacement%20Canopy
You bet there are gazebo-building plans to be found on the internet! Several websites offer free plans to help you build your own gazebo. This website has free plans for a variety of gazebo styles: http://www.backyardspaces.com/gazebo.html. Summerwood Products offers a service that allows you to customize your gazebo online and then get a plan for your custom gazebo, but I believe there is a fee; here is the link to their service: http://www.summerwood.com/cdn/plans/gazebos/index.html.