Relatively simple large bulk storage shelves for the basement. Each shelf has 3'x8' of storage area, all built with cheap 2x4 lumber studs and a couple sheets of on-sale hardwood paneling :
5-Tier Storage Rack 170x28.5x170 cm Solid Pinewood – homedecor24
DIY Storage Shelves with 2x4s and Plywood - The Handyman's Daughter
vidaXL 5-Tier Storage Racks 2 pcs 170x38x170 cm Solid Pinewood 500 kg | vidaXL.co.uk