Vintage Clothing Deals

So there's this really expensive vintage store that I like to frequent. They have an incredible selection of gorgeous items, but they're anything but cheap.
Anyhow, they have a bunch of sections. You know, one section of 1940's dresses, one of 1950's dresses, 1960's and so on. Of course the older the garment, the higher the price. It makes sense.
I notice that every so often, some of the clothing gets mixed up. For instance, once in awhile I'll find a 50's dress in the 70's section, which means it's marked at the 70's clothing price. I don't know how they get them mixed up, but they do.
So when I got there this weekend, I headed right for the 1970's section. After flipping through about 50 polyester dresses, I see it. A long velvet gown with a floral design and sweetheart neckline. I knew right away that this was no 70's dress. It was very similar to the gown pictured, except it was black and red. I examined it further, and concluded that it was from the 40's. Price? $45. It was after all on the seventies rack. The 40's rack averages around $100-$300. Obviously I was going to buy the dress either way, but what made it even better is that it actually fit. When I brought it up to the register to pay, I asked the sales girl how old the dress was. She looked at it and confirmed that it was forties, and then said "you better buy this right away, it was in the wrong section!". That made my weekend for sure. She then told me how she went to this thrift shop not long ago, and found an authentic flapper dress for 3.99! Anyone else found amazing deals on vintage clothes?