In my opinion, if you want to buy luxury sunglasses, you must buy classic style. This kind of sunglasses usually represents modest luxury with no exaggerated decoration. If intend to buy a normal brand ones, you can buy big frame ones with tawny lenses which without edge angle. The simple one without glitzy decoration will always be the point that needs you to remember, because this decoration will soon get outdated day after day. To avoid the logo appear in obvious places if this sunglasses are common brand, because this behavior will be a little awkward when you go out.
If you want to buy sunglasses for last for a long time, you shall try retro vintage sunglasses or some classic sunglasses. For example, aviator sunglasses, wayfarer sunglasses or cat eye sunglasses and so forth. They are not fresh design sunglasses, but they are still popular in those years. So, want to buy a pair of sunglasses for last long time, you can try such vintage or classic style sunglasses.
If you want to own the sunglasses that never go out of style, you'd better choose to buy the classic type, like the oakley sunglass. In order not to go out of style, the oakley big frame sunglasses have high quality. This type of sunglasses will always make you look young.