As a test, I bought some pullup bars to sell at the gym but as it turns out, i can't use them at home. It's the iron Gym model that fits in your doorway and allows you to do stable pullups.
Here's the thing I did NOT know: your doorframe MUST stick out of the wall for this to work! My doorframe at hoem does not stick out of the wall as you can see below:
And I'm guessing that some doorframes in houses around here won't either, meaning the pullup bar will slide down as there is nothing to stop it when you do pullups.
My loss, your gain. If you have a door that can hold these (with a frame that sticks out) then I'll sell you one at cost: NT400. I'm not making any money on this and I only have 3 for sale. No returns, no execptions. These are new in the box. Call me today if you want one!