If you have a set of plans that were designed for a scratch type build, the cabane wire fabrication will be there. For kits, you never know. Some companies provide everything you need in case something breaks in a crash, others not so much. Cowls, canopies, and wheel pants can sometimes be purchased through Fiberglass Masters or one of the other fiberglass parts houses. If you don't see it on the website, you could try calling or emailing them about a canopy. There is also park flyer plastics for canopies. He has tons of them.
When I build from a set of plans, I usually fabricate the cowl from scratch. I can also make a canopy if I need to, although that is a lot of work. The trick to scratch or short kit building is looking for those hard to make parts you don't want to tackle before you fall in love with the plane. And with bipes, they usually have a windshield instead of a canopy. Those can be made from a piece of clear plastic and a pair of scissors.
Carl