Adjustable dumbbells
Or, get a backpack and a bunch of objects. Been doing this for ages and love it. If you want a particular weight, 2L soda bottles weigh 2kg, and you can use coins/change if you want more than 10kg.
pullup bar.
A decent doorway pullup bar is the iron gym. I also use this for pushups with a wider range of motion and a "bench press" style grip. If you want to fatigue at 5 reps, just wear a weighted backpack, as above.
This one??
http://www.amazon.com/Iron-Gym-Express-Chin-Up-Bar/dp/B003VNAKEE
I think I ordered almost that exact same model with Walmart's ship to store program for about half that price. Let me go look.
*edit yep this is free site to store pickup, $10.50 no shipping charges.