https://www.amazon.com/dp/B01F47TTK0/ref=cm_sw_r_other_apa_SArBBbFZPFZ6F

These are what I wear. They're fairly good at moisture wicking and breathing. Since I'm MX in a hot climate, my sand tees get trashed quicker than average. At $3 each in bulk, they're a steal. You can also try and sell some to your shop if you don't need 12.