I HAD to share when I saw this! I'm "off season" from my first pregnancy, so even the clothes I had were "wrong" for size/season ;( Our local thrift store has honestly been a GREAT resource - I've popped in as often as I can during their once-a-week 1/2 off sales and have gotten LOTS of necessary cold-weather gear that I didn't need for my first :0
That said - we were at a yard sale Sat. and there was an Old Navy Maternity winter coat and I hesitated for a minute and thought "Will I really NEED a maternity COAT?" and the woman said "It's $1 if that helps" - SO DID - of course I bought it!
I tend to like Old Navy's Maternity styles, etc. a lot - but only can buy on line now ;( I know hitting that right at a Yard Sale is one-in-a-million - but I'd think of Ebay, Craigslist, Yard Sales and Thrift Stores SERIOUSLY! I've gotten a few sweaters/jeans/cords - cold weather stuff I'll totally need! And I don't mean compromise to get it cheap - I personally try on almost everything/when I can
I bet for the coat specifically Craigslist - could post it in "Baby" as a wanted item...or probably Ebay would be good too!