I usually wear just a regular T-shirt, but it's getting really really hot, especially at the gym where I play at. So, does anyone have recommendations on what kinds of shirts to buy? Doesn't necessarily have to be designed for badminton, shirts for all sports will do. And preferably, something around 20 bucks? I found an under armour loose fitting training shirt for 20 bucks, but I want to see what other options there are.
depends where you are and what shops are available near you, it also depends If you are willing to order online.
Some Football (Soccer) shirts that are on sale at the end of the season or that they are selling off for new stock are good. I got some good football team shirts by Adidas for £7.50 each and they have airflow panels which are better than normal shirts.
I would suggest any polyester t-shirt, such as a Nike Drifit shirt or football/soccer shirt. You should be able to find these at any local sports store for less than 20 bucks. You can also order online as well, the sizes are pretty standard.