Hasn't got to be expensive, Ikea for example but id never just set it on the floor. id end up booting it at some point.
Anything directly on the floor has the ability to have beer thrown directly down into it.
It has happened believe me and it wasn't a pretty outcome.
If you have several pieces of equipment a rack is essential.
However the need for the quality of those the OP aludes to is pointless.
i would suggest that, depending on what kit you have, it needs to be off the floor with plenty of room for air circulation and if you have a certain type of turntable it needs a separate shelf probably wall mounted.
The Townshend Racks referred to earlier are excellent but completely pointless in a reasonably priced set-up.
The addition of a rack of this price into any system on a moderate budget os pointless.