I imagine most bitcoiners wanted logo-free clothes before it was cool. I've been buying blanks from wholesalers for a long time, but brands still play a role if quality matters.

Lightning Store turned me onto comfort colors so I've been buying my blank pocket tees from them.

Otherwise, I buy run of the mill Levis for pants and cotton Hanes hoodies. I've been on a pajama top kick for awhile and buy those used on eBay.