A 10 foot gutter will give you 4 30 inch pieces for about $7.00. 8 caps will run about $24.00. The proper glue is a few dollars. You can do 4 for under $35.00. The plexiglass can be expensive. I bought mine at a plexi wholesaler. They had large pieces which were scratched on one side, so they were cheap. I think I ended up with 4 28x28 pieces for about $40.00. Some of the damaged ones were larger but they trimmed them for $1.00 a cut.
What I like about this method is what you can do with it. In addition to the sloppy toner application I mentioned, I also did some bleach/toning using a paintbrush, just around the edges. I rotated the plexi so I just painted on the bottom, having the chems drip to the edge of the paper. The central part of the image remained untoned. The edges were toned in a funky way, with brushmarks, and variations.