Supplements:

Be careful with doses and allergies.

Caffeine: Can increase cardio performance.

Creatine: Drinking more water is needed. The most proven supplement in sports, helps short turn energy systems(ADP>ATP). Can increase repetitions in the gym and body weight due to increased water weight.

Multivitamins: Non toxic ones(check to see if any vitamin is toxic) These can be a cheaper source of vitamins and minerals compared to fruit and vegetables.

Cod liver oil: Joint and brain health(you probably don't eat enough fish).

Protein shakes: Can be cheaper, easier and quicker than food.