Does country of orgin matter?
Yes, it does. As others have said, while it's certainly the case that Chinese seamstresses and seamsters are capable of making superlative shirts, most Americans will associate Chinese-made clothing with cheaply-produced crap. You're going to have to do a whole lot of evangelism to overcome this perception, and even then, you'll probably find that it's harder to sell than something made in Italy.
I am currently designing a custom shirt line to be made in China. These shirts will deliver within three weeks and are nearly handmade. The quality is superior to Borelli, Barbera, Etc...These shirts will retail between $100 and $250. This is nearly half the price of the above mentioned shirts.
I'd be interested to see the rundown of the features that make these shirts superior to Borrelli, and I'd be very interested to see the finished product.