30A circuits limit your PSU at 3x 1200W (7..8A - 1500W each at the wall) power supplies per circuit in continuous load. I'd rather go with multiple receptacles of 20A (good enough for 2 power supplies each), and not using those expensive PDUs.
Overall is cheaper.
Just to be clear, when you refer to a cheaper 20A receptacle vs a more expensive 30A receptacle, you are referring to a 20A 120V receptacle vs a 30A 240V receptacle right? I just want to be sure, because there are 20A 240V receptacles also.