So, I've been keeping saltwater fish for close to 20 years now. Ever since the first time I saw the Blichmann HopRocket, I was thinking I could make something similar. In the fish hobby, there are products called "Media Reactors". They are usually plastic and PVC enclosures. Water flows into the top, down a tube and output at the bottom of the enclosure, it is pushed up through a screen (and sometimes foam which I would remove) and filtered through media (carbon, phosphate remover, etc), then through another screen and out a fitting at the top. It withstands pump pressures up to 30 gallons per hour and is obviously air tight. Seems to me, this could work as a Randall if it simply sat between the keg and the tap. I'm sure the barb fitting would have to be adapted, but I think it may work. I wouldn't trust it with hot wort, but in a keg system, it could do the trick. Would be a heck of a lot cheaper than $125. Here's a link to the product
Can anyone think of an obvious reason why I may be barking up the wrong tree? If not, I may give this a shot.