I use a box fan with filters taped to each side. You want to do both sides or the air gets pushed/pulled around the edges of the blades, rather than going through the filters.
It works with two and not with one, so pretty much required. The effect is far from marginal in my setup. Also far cheaper then the post link, less than half.
The net effective increased filtration rate is marginal.
If you can afford this without concern, it's fine, but it's not necessary.