8×8 Portable Greenhouse 8x8-Portable-Greenhouses Image 5 of 5 $3,491 Plus Tax and Delivery. 8×8 Portable Greenhouse. 6×6 Timber base w/Pressure Treated Framing, 2-24×27 Windows, 8mm Poly Panels, 5′ Walls, 7/12 Pitch Roof, Composite Trim Painted Your Choice of Color. Rent to Own available 36 Months $171.32 Per Month.