@desea It will really depend in the fabric and stuff. Learning the skills needed takes time for sure (like with everything).
But going with something simple as cotton and doing a shirt with like cheap cotton you might end up cheaper. If you need die and print that cost might be higher though.
Jeans denim I remember being quite expensive and you might need better/extra equipment to handle the thicker fabric and special very durable stitches.
The Cosplay I posted not to long ago uses like 10€/m cotton. both like a tad more than 60€.
The more special kind of fabric I wanted for cosplay cost a little more since its imported (thank you brits leaving the EU!) I am looking at about 100€ in material alone. Not withstanding stuff like Buttons and small things.
Economy of scale is a real thing in clothing plus sweatshops. Margins are insane