thrift stores, Goodwill and Salvation army are alright, but they end up being too expensive at times. So look for privately owned and local thrift stores, the one in my town sells a 3 piece suit for under $10. at Goodwill a suit jacket is $30
joanns, local fabric/sewing stores, craft stores..anywhere with a sewing section would prob have patterns.
i personally prefer making my own patterns as opposed to buying patterns unless i really have no idea how to go about making something. the patterns you buy can be such a pain in the ass! ugh..