The biggest mistake we see in older Green Bay patios is shallow base prep — 3" of crushed stone where there should be 8". When the ground freezes 40" deep in February, that shortcut shows up as cracked joints and tilted pavers by April.
Every patio and walkway we install starts with proper excavation, geotextile fabric, 6–8" of compacted ¾" minus base, 1" of bedding sand, polymeric joint sand, and edge restraint. It costs more on day one. It saves you a re-do in year seven.
Concrete paver patios typically run $22–$32 per sq ft installed. Natural stone runs $32–$48 per sq ft. Retaining walls are $50–$95 per face foot depending on height and engineering requirements.