Cheap boss farming: when fighting a boss, focus all your power on killing it, then take the huge amounts of money it leaves behind. let the tanks it spawned destroy your base, so you can restart the level and fight the boss again! + if this helped
Any one who has not tried out the demo of raze 2 must do it. it's at raze2.net, and has totally awesome features. there's awesome graphics and stuff like "crotch shot! +15". can't wait for it to come out!
It's notable that while the missles suck when partially upgraded, can totally dominate higher lvls on full upgrade (plus then, its comparitavely cheap)