These pages contain some good info.
Some of them require an invest of around $10-100+
It all depends on how you scrounge together the required items.

Do upper body and lower body exercises. Rest 1-3 days a week depending on the intensity of your workouts.
Checkout Stronglifts.com.
Dont focus on having lots of gadgets.Focus on using what you have.
The main thing is to get started and be consistent.
References :