I know this has nothing to do with a dip rack, but like eric mentioned perhaps you should get something that essential like a kickass powerrack. something like this bad boy right here http://www.newyorkbarbells.com/pro92600.html

you can squat from it, bench from it, deadlift, and do tons more, plus it has a bar on the side and front that you can do pullups from and then work your abs from hanging on the pullup bar