For the most part, the price of a shirt made in India vs USA is the cost of labor. The Indian woman will work for $3 per hour which is a decent wage for that area (don't fact check me, it's just a guess here). She can probably make 5 shirts an hour.
A woman in the United States will make $16 per hour and still make just 5 shirts (or less - more rules in the US about breaks, and probably streaming Netflix too)
Now the company that sells the shirt at Walmart for $10 will have a profit margin of probably $5 per shirt from the Indian labor, and $1 from the US labor.
Technically after the industry is built out more we may be able to squeeze more shirts per hour if we start doing technical innovations (for example we make a machine that pre-sews 5 of the seams because of innovation. This is something that won't happen if the center of gravity is in India, but may happen in the US. (Actually today that may happen in India as tech is taking on its own thing there now).