The ShopFox track saw (or Grizzly) is usually the cheapest.
Dunno how good that one is, but the online reviews
suggest it is effective after making a few tweaks to it.

The Makita and Festool models are the cream of the crop,
with the former priced at about half of the latter,
and no significant difference in quality or performance
(I have used both, and bought the Makita for here).

There are also "track" thingies to add to a basic Skilsaw,
but those are not at all the same as a proper track saw.

A track saw track, has a (replaceable) zero-clearance edge
at the cut line, so no top splintering of the material,
and really easy set-up: just line that edge of the track
to exactly where you want the cut, and that's where it will cut.
No weird offset measurements or anything.

So anyone starting out, or looking for an upgrade in saws,
take a good close look at track saws. They really are fantastic,
and can replace a tablesaw for many purposes. They can
actually cut straighter lines, and on crooked materials.