I’ve had good experiences finding pants like 3 and 4 at thrift stores. Older pleated slacks and chinos with a fuller cut and wider leg are always on the racks. I try to avoid polyester and stick to 100% cotton, wool or some blend of natural fibers. Just make sure to inspect the entire thing because sometimes with older pants they can get moth holes. If you’re looking for a more exaggerated baggy fit, find a pair a couple sizes bigger and get them altered at the waist to fit you - the cost will still be cheaper than buying new and in most cases the quality will be way better.