Certain churches and church groups, including sometimes St. Vincent de Paul (for example), as well as certain community centers, sometimes offer free-for-all clothing along with their foodbanks, as well as other yard sale type items that are regularly donated. This is especially true in the Northwest Pacific region of the US. This stuff, including clothing, seems to get rotated fairly rapidly, so if you don't see what you like on one visit, you'll often find something on the next visit.
If you are very selective, Goodwill, Value Village, and other thrift stores (as well as yard sales) are fabulous places to get really nice things on the cheap. One thing about clothing from Goodwill, though, is that is smells awful! I've had things air out on the line for two years, and the smell still was not totally gone! A quicker way of removing other people's fragrances is to soak the clothing in a 5 gallon bucket of water, changing the water, daily. After a couple of months, at least a majority of the fragrance will be gone, but probably not completely.
If that doesn't work, there's always dumpster diving! Good Luck!