Although often overlooked in the strength community, I consider the plate holder to be an essential tool for any weight gym. Owning one or two holders can go a long way to keeping your weights well organized, accessible, and off of the gym floor when you are finished with them. Sure, you can pile your iron all over your training area and forget the plate holder, but I have found that a well organized gym is more functional, more efficient, and more psychologically pleasing than a messy lifting facility. For these reasons, owning a quality plate–holding apparatus can help you have more productive and more enjoyable workouts, even though its effect is indirect.
The drawing below shows a typical standard weight plate holder, and its construct usually allows 300 to 500 pounds to be held safely. Note how the plates are positioned so that they can be gripped and removed from the rack without excessive back bend and with minimal effort. In contrast, lifting heavy plates off of the floor each time you want to load your barbell not only wastes valuable energy, doing so also can lead to back strain and in a bad way.
A new and quality standard weight plate holder can be bought for $50 to $75 (plus shipping costs, if ordered for delivery), although I suspect that units for Olympic-style plates may hit your bank account a little harder.
I bought my plate holder at a second-hand sporting goods store for relatively little cash, and I suspect that you can do the same if you are willing to shop around. You can also search various online services and, perhaps, find a great plate holder for just a few bucks. Of course, if you can weld and work with metal, or have a friend who can, then this gives you even more good options.
Yours in strength and health,