I believe this is roughly the
I believe this is roughly the price list now (no guarantees):
Invisible shoes -- $25-30
Luna kit -- $25+
Bedrock -- $35
Branca -- $40
Unshoes -- $42+
Not including shipping, which will differ by company. Kits (including Invisible shoes, Luna, and Branca) require you to do some cutting, which can mean rough edges, if you're not quite careful (more important for casual use). Bedrock and Unshoes require you to provide custom measurements, which they use to fit the sandals, themselves (iirc).
(Invisible shoes and Branca are sort of halfway -- they provide a rough fit, but you have to trim the front, especially for Branca. Luna does have custom-fitted options, but not for around $35.)
I only have one pair now, using a standard Luna kit (6mm neoprene soling material). It works well, and it looks fairly decent, although I have to say that I was borderline obsessive about cutting the sandals out of the material. If I hadn't been, they would probably look somewhat sloppy. But that's partially a reflection on the thickness of the rubber (6mm) -- I don't think the thinner Invisible shoes or Brancas would have been as difficult.
All that said, I don't use them on trails. You can choose different soling materials for the Lunas, and the "Trail nubby" is only a little more than the neoprene -- perhaps that would work better? The Unshoes were originally pitched as 'trail'-sandals, too -- thought that's a bit higher than $35.
Just look around and see what's available. Good luck.