Squat rack = pullups (tons), leg raises, upside down crunches
Then I would look online or at an army surplus store for duffel bags. Buy 2 of those. Go to home depot or lowes and buy some play sand. 40lbs is about $4. While there also buy contractor bags and duct tape.
Follow Ross's sandbag guide:
http://www.rosstraining.com/sandbagconstructionkit.pdf
Then you can go on youtube and search for Josh Henkin. He has some great sandbag training stuff. I have his e-book.