Easy $1500 On A Slot Machine
In the casino, there is a slot machine with a cow on it, put in $100 dollars to gamble and you will always win the first 5 times.
Killing The Mechanic
Save the handle bars for the bike until last to collect on your way back to the gas station. If you have opened the hunting store go in and grab two assault rifles. Go to the gas station angle level through the roof with the ladder. In the back room where the food is go back to the hunting store, grab another two assault rifles. Save your game at the gas station. Go and give Katy her Zombrex and have fun killing the mechanic. Hide behind cars for cover because he is fighting back. Enjoy.