Thank you very much Iammert, sorry about the wrong section..
Picture gallery wouldn't work, as I still need to input in a lot of criterias like price, specs, age, and other misc information inside the back-end for it to easily updated by the client's staff, via a CSV file. Also their specifications differ across the subcategories, for example used engines they'll add horsepower, and cranes they'll add lift tonnage, etc..
Hence would still require a front-end/back-end system that's a bit more advanced than an image gallery.
Would be along the scale of tractor farm equipment website, for example..