I did do some market research out of curiosity and found new jackets around $100. I understand your jacket is of superior quality with extra options that commanded a higher price when new, but sellers must compete in the market that exists at the time, as many home sellers discovered in 2009.
I bought and sold a few classic cars over the years and didn’t always get my money back, so I feel your pain. You have to keep in mind you are not selling straight-jackets, you are selling a straight-jacket of a specific size, so the total pool of potential buyers is cut down to those who can use it.
I am not suggesting you give it away, but a little research that helps you put your item in a pricing sweet spot that will attract maximum interest under current market conditions and still bring the best price is time well spent. Best of luck.