I also have a question, when shelves are this tall do they need to be anchored to the wall? Ideally, this shelf unit if found would only be 2’ to 2.5’ deep.
Yes, for tall racks that are slender like you are looking for, they need to be bolted to the floor, have wall brackets and also be anchored to the wall.
https://www.steelking.com/wp-content/uploads/2018/05/SK2000_Install.pdf (These instructions don't cover the wall brackets because slender racks, like we are talking about, are uncommon. The brackets exist and the dealers/manufacturers can give you specific guidance for what you need in your situation.)
As said above, you can get used rack. However, you don't save that much and it's hard to get the accessories like you want them. (grates, brackets, clips, etc.) Finding an odd size like you are looking for is also going to be tough. (24"-30" is not commonly found in warehouses...)
I needed 30" racks for my garage (14' ceilings) and ordered a system from Steel King. There are many other manufacturers who make this style of rack, but I found them reasonable with a large dealer network. You can get the racks in any size or color. In my case, my dealer had the metal grates made by a local company.
https://www.steelking.com/ (I got a SK2000 system.)
I paid just over $2000 for a 30" deep, 10' tall, 44' long system with a "stock" paint color in 2018. (Steel may be more expensive now.) I also have a ton of beams, which drove up my cost. The fewer beams, if you build your own wood deck instead of buying metal grates, etc. then the cost goes down.
One thing to also keep in mind is that your racks don't need to go to your roof. I found 4' short of my ceiling is a good measurement. The stock on the shelf is not much taller than 2' and we keep some clear space on top of that for fire safety. (One doesn't want to stock the shelves all the way to the ceiling.) So, shortening the uprights brings down the cost a good bit, also. (I recall that fire code allows higher stocking of materials on shelves that line walls and not in the middle of the room, but we have the space and have decided not to push it.)
