2x4's are seriously underrated.  Or maybe it's just that nobody builds anything anymore.  Unless it comes from a store, it must be crap, right?  I'm not what you would consider handy, by any stretch of the imagination, but even *I* can build stuff with 2x4s.

Home gyms are expensive!  $300 for a nice squat rack or.....$15 dollars in 2x4s 
And who needs an expensive ladder from the hardware store when you can....build one for less than lunch at McDonalds?

For the record: the rack is shown holding 325 pounds (which is more weight than I see most people use at the gym anyway). What the pictures doesn't show is that I was also hanging from the bar, for a total weight of ~500 pounds! For only $15! You can't beat that. I used it for over a year without any problems or any signs of fatigue.