Production of the garment to the point of sale.

In order to produce these garments to the point of sale, I would have to explore the manufacturing industry, its production, quality, costs and ethical issues including  health and safety issues.
The factories would need to have the equipment necessary, produce samples of good quality and give an estimate of maximum and minimum production capability and its costs. They would also need to ensure that the work conditions are ethical, thereby taking care of health and safety needs and the work environment of their staff. Premises should comply with health and safety requirements such as provision of water, fresh air, fire exits, and cleanliness to mention some.   Issues of under age workers and gender equality would need to be considered to avoid exploitation and inequality.
Other important factors that would affect the cost would be the transport and storage of goods. I would also need to apply for licence to trade and register for VAT purposes.

After promoting the garments, possibly a range, proof to the interest of retailers and orders from prospectives buyers would make it easier to approach the banks in order to apply for finance.