Just be naked, same effect, less money in my experience. (Unless you mean like underwear, then unfortunately we're stuck, but everything else, yeah, thrift)
this is funny but it's definitely not remotely true, imo. There's loads of good retailers out there, from small-time Etsy sellers to full-on brands. Goodonyou is a great (albeit, not exhaustive) directory for sustainable fashion brands.
The downside, of course, is that they're often more expensive.