Buy something that will increase the comfort and minimise the risk of losing your medical.
Therefore, a good pair of sunnies that minimises colour distortion and limits the amount of UV light transmission. They don't have to be expensive.
I would definitely invest in a good, well fitting headset. Your ears are vital and it is very easy to lose the medical because of "deafness". Buy the best one you can get. I have used a David Clark 10-20 for the past 15 years and my hearing is still good. Look for rugged design, good quality components and the ability to be repaired. Many of the so-called cheaper ones can't be.
If you decide not to fly, you can easily sell them.