First of all Energy Boost (Pizza) you should get at least 4 of this. This will allow you to gain 100% energy instantly. This card refreshes 24 hours after using it. This card cost around 10,000 starbits
Next is Pizza Box. This card will give you a chance to store free Pizza (Energy Boost) while doing Missions. It's like a storage of energy.
A quick tip, Illegal Busking Mission in Map 1 (Home Town) has a higher chance of dropping / giving a discarded pizza (Energy Boost).
Lastly card is R100 Pixie a rare card valued differently. I bought this one for 10,000 starbits. A decent card for boosting stats. 200 fans + 100 skill is the max stats for +fans stats a rare card can give i guess.
In Music Instruments Card i leave it to you which one do you like to purchase.
I'm not an game expert and this guide is not a financial advice. Please do your own research, and think many times before buying something in the marketplace.
Thank you.