I managed to get a fair few clothing items from Century 21 when I was there, RLX, Adidas and & TW Nike tops all less than $20. It's like an organised version of TK Maxx, but does mean that it's very hit and miss for what they have in stock.
The Nike store had the new, top of the range gear but it was still very expensive. Almost same price as back in the UK.
To be honest as there are so many web sites over here doing sales most of the time, and places like Sports Direct and TK Max selling golf clothes on the cheap then it isn't much cheaper to buy golf stuff in the US. Yes you may be able to get clubs slightly cheaper but is it worth the hassle of carting them back?
You're in the greatest city in the world, see the sights, don't go shopping for golf stuff.