How to Make a Petunia Tower -- Basically, it's a ring of galvanized fencing lined with landscape fabric, then filled with potting soil. The petunias were planted through slits in the landscape fabric. This looks like a pretty easy do-it-yourself project!
A Framed Lobelia. Like the framed hanging basket idea. Use turquoise or purple Mor Perfect idea for front porch: eye hooks in old frame, hang frame with jute from hook, and center basket filled with favorite shade lovers
Garden Gate Planter (An old gate would be hard to find but places like Menard's sell small sections of plastic or metal garden fence that would work. Or haunt rummage sales for something to upcycle into a backgroud for the flower box.