You can purchase singlets for competition through the PowerSports Wear Company. They have a cost of $45 + shipping.
You can find the purchase link here
They have Womens and Mens cut, womens have a high neck line, mens are lower. As for the size, we can bring in some "test" singlets for you to gain an accurate idea of the size you will need! We will communicate sizing day through the SportsYou.