I made one too!
Works pretty good for about $10 in materials. Even less if you already have some of the parts which I'll bet most of us do. The only extra part I bought was the wire mesh strainer. I spent a total of $5, not including tax.
However, I can see buying the real one if you do lots of dioramas or very large diorama layouts as many "train" guys do.
I used a slightly different set of instructions. Its the same as the video except the large brown capacitor and blue r4 resistor are removed. Supposedly it makes it more powerful. I dunno, I have nothing to compare.
I bought the strainer at Family Dollar. You get both a 3in and a 4in diameter for $1. I drilled holes (2) in the plastic handle of the strainers and fit them over the two pegs that the screws go into at the top of the swatter. This results in a nice very tight fit for the strainer. No shiming necessary.
For simplicity I used an alligator clip to attach the positive wire to the strainer.