The choice largely depends on what the wall will be used for. For example, with Leca as a retaining wall, more reinforcement might be needed, possibly larger blocks, etc., than for a freestanding wall.
Regardless, I have received the following prices (approximate):
Lock-Block XL: approx. 1300:-/m[sup]2[/sup]
Leca including plaster: approx. 1000:-/m[sup]2[/sup]
L-support: approx. 2000:-/m[sup]2[/sup]
Prices apply to walls used as retaining walls, including labor, drainage, and excavation. We chose Lock-Block XL, which is, in my opinion, an attractive and relatively inexpensive wall.