grasscrete?

dirt

or

http://www.omnipropittsburgh.com/turfstone.html

I first saw this product used at the dia Beacon. They use it in parking lot and turnaround. a great product that allows drainage but still maintains level wear proof surfaces plus the wear of the grass in more traveled areas creates a great variation across the terrain

I think there some plastic versions which have no upward face (if you know what I mean). I don't think they take heavy traffic but should be fine with cars.

depending on the climate, there are various polymers that can stabilize the soil that are the cheapest alternative.

geotextiles and rigid cellular reinforcement is next up in cost - I'm not much of a fan - they're plastic and not pleasant to walk on. but they are previous. you can plant grass in them (with variable luck) or use a decomposed granite/gravel fill

flatwork is the next price point - asphalt can be cheaper then concrete for small projects - but all depends on the local mixing plants and contractors

pervious concrete and asphalt require substantial subgrade work to work and must be perfectly flat. and are more expensive because of the rarity and specialized installation skills

unitized pavers - concrete, bricks, stone are the most expensive cause of labor. material costs are significant too, especially once you get into stone. popular stones are granite cobbles/setts, bluestone flagstones. masonry can be either a rigid installation (concrete slab backing it up) or flexible over a compacted sub-base - flexible is cheaper.

grasscrete is a variation of unitized pavers with a flexible base

I have also seen wood logs as driveways in arid locations.