What can I wear to my first classes? There are a few gyms in my area that offer trials so I am thinking about starting BJJ and finding a gym that works out for me. I don't really want to invest $100 in a gi quite yet because I'm not 100% sure if it is for me. 

My question is, what is appropriate to wear to take a few classes at a new gym? Will I be expected to have a gi walking in the door? 