My Brother shops at Goodwill all the time (cough) reselling the stuff on eBay
I guess your brother (cough) is at least letting Goodwill get the first round of profit on the items, if he’s buying them from Goodwill.
That doesn’t bother me at all. I see people at The Salvation Army every half-price day picking out the resaleable items.
I recently paid $4.50 for a dress for my 3-year-old. It still had the tags on, and we found it listed for $178 retail.