Fabrics purchase
The price here may vary greatly. For the brand that I described, the price per meter of basic fabric will be $ 10-30.
But there is also a lining, accessories, applied materials, like glue, shoulder pads, hems, threads, etc.
For a dress that cost per $ 25 for production, you should expect to spend a minimum of $ 10 per piece on fabric, labels, packaging and similar costs.
Batch production
Of course, it depends on the quantity, fabric and requirements for sewing.
Price per item will be $ 5-50 depending on the place of production and the thing itself.
Producing a simple piece of dress in the USA would cost you an average of $25 but in China, you may be able to get prices as low as $15 especially if you are manufacturing up to a hundred pieces.