Use of hollow blocks ( concrete here, could be terracotta , jali etc ) as an entire wall - to frame semi indoor outdoor space done very effecively. Possible low cost solution - privacy, windflow, aesthetic, Gerrit Rietveld pavillion at krollermuller museum via paulkomada
Root Cellar - the author said it cost about $1,000 for this 8x8 foot cellar: concrete blocks were $1 each at the time, and he used about 320. About $500 for concrete and mortar, and the remainder for rebar, wood, etc. He contacted a local gravedigger to use a backhoe to dig out the space for the cellar.