I’ve bought three pairs of Ray Bans totaling for less than 100€. I don’t know what second hand websites/apps you have but I have a 30€ limit on search term “Ray Bans” and I get multiple hits every week.

And if I don’t end up liking or using them as much as I thought, I can just sell them for the same price or give them as a pretty higly valued present to a friend.