This site over-simplifies things IMHO.
I did some work with Electrolux (on vacuum cleaners, funnily enough) when I was studying for my degree in industrial design. It transpires that two key things affect the effectiveness of vacuum cleaners, and neither is the size / wattage of the motor.
One is the stainless steel plate underneath the 'brush' end of the cleaner. The grooves in these plates, and the radii on their edges are (down to .01mm) critical in how effectively the cleaner operates. There are (or were) only a couple of manufacturers worldwide, producing these plates and supplying them to vac cleaner manufacturers.
The second, and more relevant to your use (which I see as more extractor / less vac cleaner) is the weave of the material used for the bag. Once again, this is a highly specialised / dark art, the knowledge of which lies with a handful of companies worldwide, who produce the material for vac bags to sell on to vac cleaner manufacturers, in addition to (perhaps unsurprisingly) producing material suitable for the manufacture of tea bags - it's all about filtration - innit - and I suspect that people who have invested heavily in finding out what works and what doesn't, aren't likely to give up that information readily. Hence, it might not be so easy to acquire the material you need.
I'm interested to hear how you get on.
G'luck.
J