Looking for tall metal ramps

I am on the hunt for a set of ramps that are taller than the typical ramps. I think the ones I have rise about 8 inches, but would love to get a safe way to get my car up somewhere around the 18 inch, or more, area. They will need to be a lot longer than normal, to keep the slope low, but that's fine.

Does anyone know where I can order something that will be useful like this? For a while, I was "dreaming" about a lift, but my garage roof trusses are only 9 feet above the floor. That would really only give me about a 3 foot rise, but the cost is too severe.

Metal would be the preferred material. All the wood ramps I see get really heavy.