A common way to wear them is with vintage granny boots for a romantic style or 70’s style wedges for a bohemian theme. I have a black vest that I wear with one of my lacey Gunnies and it tones it down. I have seen some people wear leather belts to make them less formal as well. I hope this helps, you can always go on lookbook or other fashion websites and search gunne sax and check out how ther people wear them!
Sorry for the delay on the answer we took a brake away from tumblr. The best way to know how much it is worth is to go on websites like ebay and etsy and search similar ones and average the price. Gunne Sax dresses in good condition are worth anywhere from $35-150 online and $45-80 in Vintage Shops. The larger sizes like 9,11, and 13 usually have higher demand so you can sell it in the higher range. If it has a black label then it is probably worth around the 100’s depending on the style. I hope this helps!
I just wrote this extended article on tips for identifying authentic and true vintage Gunne Sax dresses.