If you have transport, there's plenty of free used materials going. I've made a path from roof tiles!
Perhaps the raised beds could be repaired with wire mesh behind any cracks and stabilising plants? I've used violets and bell flowers to fix the soil on banks with their long roots.
Maybe think in terms of reusing as much as possible. The retaining walls could still have many good blocks that just need resetting with new cement.
Recommendations please, for a stopover on the way to Loch Tay