There is lvl 1 gear you can make or buy from NPCs in the starting towns that you can get something "close" to the Black Tee from.

Hempen blouse, Hempen Tunic I believe...

As for the shorts...
Try looking at some Subligars, some are actually shorts and not speedos.
The Coliseum gear and it's dyeable lvl 1 clones may work for the shorts.

Sailor Shoes may be the closest you can get to gym shoes.