Industrial grade steel storage rack as audio rack?

I've reconsidered. Definitely don't do it. Instead try putting together a "custom" Ikea Lack equipment rack. The Lack side table retails for $13 and you'll need 2 or 3. Here's a link to images of what people have done with them as equipment racks. With a little imagination, a drill, some spikes, a saw and sorbothane you will have a far, far better rack than what you're contemplating and do it for less than $100. You can probably even use you Timbernation platforms.

Over the weekend I dismantled my DIY equipment rack built from slate. If you were anywhere near you could have the pieces and put it back together. Not the prettiest rack built. But talk about something that doesn't ring; knock on the slate and you get the dullest thud possible.
Check my system pics if you're interested.

I keep my turntable and related gear on a massive 2 foot high solid oak coffee table I picked up years ago in a second hand furniture shop down south for $30.

My amps rest on an antique wood footstool I picked up a couple years ago in a local antiques shop for about $25.

Used Furniture stores, flea markets, etc. are good places to look for effective older things to put your audio gear on if on a budget.

If it's a product marketed towards audiophiles, you can be sure you will pay a premium. Whether its worth it or not is up to the individual.

That rack is pure garbage!!