I am kinda cheap, so I have been finding materials and making them work. Here are some things I use:
Dubbing - Dryer Lint (free)
Feathers - I find them in the park (goose, duck, common birds)
Silly Legs - Cut up an old bungee cord and use the rubber strands.
Craft Stores - My wife loves to do fabric crafts. I hit up the stores with her to find cheap marabou, beads and other random stuff.
Popper Bodies - I have been using ear plugs. Bright Orange foam ones that I had laying around.
I haven't tied a fly yet that a fish hasn't gone for. No perfect fish magnets yet, but I am still working at it.
I will have to say my favorite commercial fly so far is a size 10 Betts Frugal Frog. I always catch fish with that one. It is my go to.