Gender is a silly thing. People just make it up. Take pink, for example. In just a few decades in the UK it went from gendered very strongly masculine to gendered extremely strongly feminine. Or skirts. Extremely masculine in ancient Rome. Only legionaries wore skirts. Other manly men usually wore a very short dress, which was a strongly masculine item of clothing (togas were very formal clothing and not usually worn most of the time). Still very gendered - above the knee was masculine, below the knee was feminine. Why? Because people made it up.
Fashion is a silly idea too.
Gendered fashion is silliness on top of silliness. Nobody should care about it.
As for the "bargain" price, well, I have a special offer for you! If you like, I'll buy a £5 pair of sunglasses, put a £200 price tag on them and sell them to you for £30. An even better bargain than these "£300" sunglasses!