Here's a quick guide to common path materials that can be loose-laid. Prices are approximate and do not include edging or base materials such as sand or gravel.
The easiest paths are laid over packed sand, or a combination of sand and gravel. More difficult to build are those set in concrete or mortar; such paths usually call for expert installation or guidance from a book like the Sunset Complete Patio Book (Sunset Publishing Co., Menlo Park, CA, 1998; $19.95).
Stone (cut or irregular). Flagstones make wonderfully formal walks, while flat fieldstones work best in informal steppingstone paths. Cost is $30 to $100 per square yard.
Aggregate and concrete steppingstones. Textured concrete or aggregate steppingstones are attractive and have good traction in icy conditions. Cost is $4 to $7 per 16-inch-square paver, or $20 to $35 per square yard if you butt them together.
Grass. Works best in combination with stone. Alone, use it in wide swaths that spread out traffic to prevent worn trails. The heavier the use, the more you'll need to fertilize and overseed to compensate. Costs less than a nickel for enough seed to sow a square yard of ground.
Bark. Good choice for woodland gardens, since it has the look and feel of forest duff, but it must be renewed frequently. You can cover a square yard of path 3 inches deep for about $1.15 to $4.
Crushed rock. The irregular shapes of the crushed particles allow them to pack well, giving a firm surface that can easily support a wheelbarrow. Let crushed rock pack down by itself or rent a compactor (similar to a jackhammer, but with a flat foot) to do the job for you. Cost is about $1.40 to $2.25 to cover a square yard of path 3 inches deep.
Brick. High-fired all-weather bricks are a great choice for formal paths. Most are 4 by 8 inches, give or take 1/4 inch in either dimension. Enough brick to pave a square yard (about 40 bricks) costs $13 to $26.
Pavers. Available in lots of beautiful patterns and textures. You can mix and match pavers of different colors and sizes. They cost $20 to $30 per square yard.
Gravel. Makes a fine natural surface. But because gravel particles are round, it isn't great for heavily used paths; the particles shift as you walk on them. Most is sold in the 3/8- to 3/4-inch size; smaller grades are usually easier to walk on. Cost is $1.40 to $2.25 for enough gravel to cover a square yard of path 3 inches deep.