I buy most of my dress clothes from Goodwill, some stuff still has the tags on em. Neckties for $2 each is a win, I have numerous RL ties and found a Christian Dior tie there too. Like dude said, take it to the cleaners. I'd rather buy my jeans, shoes, and t-shirts else wear though.
Most of you guys aren't gonna believe this, but I've found several Armani and Versace suits at different goodwills in affluent areas. I just recently copped a Paul Smith joint last week. You'd be surprised what you can find at thrift stores.
Took them joints to my tailor, now I can get clean in an Armani suit like it was made just for me. All for the whooping price of 30 bucks a pop.