18x24 carport on slab? or pole building?

[Soundguy]

my 53x31 has a metal track and that track has 34 hurricane die townsscrewed into the ground.

soundguy

 

[bruceha2000]

I know the size is small, but there's no way I can go much bigger. I need space for my small tractor, workbench, mower, welder, some shelves, and some open space to work in. Implements will stay outside.

You don't say where you live. If it freezes, I don't think you will do well with a slab unless it is supported by frost walls. Getting REALLY expensive now. My in laws had a large 'pole barn' garage, probably 24x36. 3 bays on one side for the 2 cars and plow truck. A small bay on the back side for the riding mower and 3 enclosed bays - WWII era generator, chest freezer, garden tool storage. All bays with vehicles were open in the front. It had a dirt floor except for the freezer room and was fine for decades. Gets pretty well packed down I guess. Amazingly, it never got snow in the bays, I guess they figured out which way the snow blew in from before they built it. This, BTW was in Stowe, VT. Not known for warm, snowless winters.

 

[exiled]

I had a carolina triple wide for my tractor and attachments and trailers. What I did was stack down cross ties centered on the carports walls. When they came and built it they stacked the the carport thru the cross ties and into the ground. The charged me extra for the 6" extra length rebar stacks. This building held up good until a F5 tornado took it apart on April 27th. I don't hold that against carolina carports because that tornado destroyed ANY thing it touched. My homeowners is paying for a new carport.
I know a triple wide is out of your budget I was just giving you the idea of using the cross ties for a footer. It raises your walls 6" and allows you to spread gravel neatly thru the carport. These carports are nice and have a lot of options. They are real durable too.