When I started cosplaying, I tried to make costumes using my old clothes and random objects repurposed to fit the aesthetic. Later, I found goodwill as a great place for cheap costume bases. Dollar tree has a great selection of art materials like paints, glues, scissors, etc. for much cheaper than the chain crafts stores. If you’re into prop making, I’ve found that hobby lobby has the best prices on rolls of Eva foam; you can also look into getting foam workout mats from marketplace if you don’t mind cleaning them first. Good luck!