Having to grind for both $ and XP is really boring, just let me buy my upgrades if I can pay for them. I want to try different loadouts without grinding for hours to level up them.
Hints for the hard badge: 1. Save the bonus points and get the anti-matter shield ASAP (lv 15); 2. Save as much money as you can: with the shield you don't really have to worry about your health or damage output; 3. Get offensive bonus upgrades (EMP, fireball, explosion); 4. Be patient. + if it helps