Around here they are hard to find and expensive, as every landscaper is
in the market. A couple of years ago they repaved a road here and as
part of that they tore out the sandstone sidewalks; people were coming
in at night and stealing the pieces, at least the ones they could lift,
and the contractor told me I could take the broken ones, but he had a
buyer for the unbroken ones.

Used bricks, on the other hand, are widely available and cheap, and make
nice walkways, but you need a good foundation to keep them smooth.

Pious Audio wrote:

I'd like to build a flagstone walkway and perhaps a couple of small
landings out of flagstone as well. I'm young and impoverished
(well...not quite, just the way that most young family men are) and I'm
interested in what I could expect to pay for flagstone (I live in
Missouri). It seems to be a pretty difficult thing to research online.

Any help would be appreciated!