Exactly, just a table cloth. Or a full size bath towel.
These products you posted look like giant rip-offs. 30 bucks?!! Get a table cloth from dollar-store it has better quality! You only need to cut it properly.
Actually, I like your idea about bath towels :P never thought about it MacMacMac!https://www.amazon.ca/Gator-Note-Ke...&hvtargid=pla-406644526975&psc=1
Now, if you want to shed some money on a cover I like these Gator covers. You can tighten the bottom of it it may look aesthetically nicer than a plain plastic throw...
And the idea to have the cover costume made is not that someone is cheap or too much time at hand, it is the aesthetics and the functionality of the cover that matter.
There is no plastic cover that sits nicely on your keyboard unless it is made for that keyboard.
You want the look, you should do it yourself.