is there a reason that prices for the lower businesses are scaling so much faster than the higher ones? right now going from 300 to 400 car washes costs twice as much as going from 400 to 500 oil companies.
step 1: go and get the gun,
step 2: go back out of the level, and keep going further out until you see the credits/score counter.
step 3: keep going out until you teleport to the boss room (center of the game)
step 4: work your way backwards out of the game, easier to get all coins :)