Golf Club -
Step 1. Go to the back of the building were the Golf would be located in Vinewood.
Step 2. There will be a male with a golf club around the back of the building.
Step 3. Beat his *** until he bleeds where his guts would make great lasagna.

Nightstick -
Step 1. Go to Ammu-nation.
Step 2. Walk in like you own the place and go to the front of the counter.
Step 3. Buy it.

Knife -
Step 1. Don't understand why you would buy one if you have one in your pants.
Step 2. Buy it at Ammu-nation.

Baseball Bat -
Step 1. Try to find the mission during Repo's with Simeon.
Step 2. Kill all Gang Members and run around on their bodies looking for one.

Hammer -
Step 1. Must have Collectors Edition

Option 1. A friend with a Collectors Edition is able to drop one for you and you are able to keep it!

Crowbar -
Step 1. Start to join Team Deathmatches
Step 2. Their will be weapons laying on the ground and one of them looks simply like a crowbar.
Step 3. Have fun hitting people with a car tool.