Rivendell's Splats are one of their nicest offerings: a shoe covering that works on any style of shoe and comes in three different sizes for a good fit. The waxed cotton means they're not completely perfect in a driving Portland rain, but for most applications they're pretty good.
That said, before Rivendell ever made their Splats, people were making their own homemade creations from whatever bags they could find.
Here's my favorite pattern, which requires a sewing machine and some old nylon soft-side briefcases (usually handed out at conferences or found super-cheap at Goodwill).
A photo of the finished item may or may not entice you.
I think the price difference definitely will.
The instructions are pretty clear and useful, and the end result is smart.
When my Splats wear out, I may just make a pair of these.