Natural stone wall/bed instead of planting rings - what do you recommend?

Hello, I am curious about your opinions and tips.
In the garden, our previous owner has currently built a complete wall to retain the neighboring property using these awful red planting rings. In total, up to 5 rows (so presumably about 1.5 m high).
In short: they have to go... Everything inside dries out, there is no flower bed, etc. etc.
My idea would be: remove everything and build 2 natural stone walls with a bed in between (so: lawn-wall 75 cm-bed-wall 75 cm). The wall would then be additionally planted in a wild and bee-friendly way. The whole thing over a length of nearly 20 meters. What do you think it would cost if a) you do it yourself or b) have a gardener do it.
For b) we will receive an offer in about 3 weeks, but unfortunately I have no idea what to expect.

Best regards

With us only 10 m approx. 1 m high, labor including excavator 2500 net. Material 800,- gives 3300,- plus tax.

Thank you very much for the response. Including concrete foundation? And do you have photos of the result? Best regards and have a nice weekend

you more or less got the stones for free, from the cemetery or somewhere else?

Normally, 1 ton costs around 80-100 euros, which is about 1 meter in a 50x50cm block.

Labor costs are about right, though rather more depending on the region.

You can roughly calculate the rest yourself.

I paid 15,- each for the stones at the cemetery administration. And there were so many that it came to about 800.

The desired photo.