What about some bricks/paver stones? Reclaim if possible to keep the cost down but no idea what that’s going to run locally for you, if even available. We picked up some landscaping edging bricks from Menards on one of their seasonal sales, interlocking approximately 12x3x3, for 75c each. Non bulk purchase from a big box store so I’d think you could do slightly better. Would be easier to install than the edging if you have the tools (Bobcat) to easily get the bricks out to where you need them, should just need to place and tap in.

$1.06 currently:
https://www.menards.com/main/b.../p-1444441410805.htm

I didn’t think of landscape timbers. They are running .55/ft from Lowe’s.

That’s actually a bit cheaper than the redwood bendable strips. I could use the timbers on the straighter portions and get the redwood bendable strips for the curvey portions.

I could cut stakes from 3/8” rebar. I’d get 20 one foot stakes from a 20’ piece at about .30 each.

I’m not finding any cheap pavers. Plus, after building a paverstone wall and patio, yikes. That wasn’t fun.

All kinds of good ideas!