I break and drop and lose sunglasses constantly, I have to buy 3 or 4 new pairs a year so I’m not interested in buying anything expensive. Until recently I bought some Chinese 5 euro crap but I would prefer to buy 10-15 euro EU made crap. Is there anything like that available?
Maybe get a glass case? I have one (two) in my messenger bag, never broke my reading nor my sunglasses, no matter how badly I treat my poor bag ;)
There are hard case and soft ones, depending your usage.