5k using J2 got me tons of fuel and other upgrades, shot myself into the air, floated back down, on HALF of the awarded 62,000 I upgraded EVERYTHING and did the same thing again, netting a whopping 132,000
I'm with zackjackel, this is terrible. Guns cost huge amounts of money and aren't terribly effective. I only survived the first boss because it didn't auto-kill my base.
Falling down the FIRST EVER pit results in an infinite loop of game overs, as the game lags so badly figuring out that the fall kills you (seriously, took it 10 seconds to decided that I'd fallen to my doom). So every time it reloads just prior to death I'm already off the screen and just get another "Game Over" message.
Defensive Wave is a pain in the ass to use, only works if you have full shields (which if you get hit they it goes off ANYWAY). So there's no way to 'bounce' more than one enemy projectile at once.
Oh, and for a game like this you should never have to do a level twice. Each level is freaking LONG, no way if I'm losing am I going to wait for death, then DO IT ALL AGAIN.