SPOILERS - Walkthrough - Rd1, make $72+, buy soda, use directly after start in Rd2, make $150+, buy 2 sodas and 1 ski, use both sodas directly after start in Rd3. Rest is obvious.
So Sparta is a piece of cake. My version is most fun - get "Old Glory" and three earthquake machines fully upgraded, spend the rest on gunman. Works on 'Hard' too.
because mrx is wrong. allways buy all sprays first, then all skis (they bounce you back very high if you fall from great height), THEN all freakies, then all creativity, then all blasts.