I've had our SteelTrak for over a decade, and just shifted it for a third time to a new site. Took les thsan an hour to rebuild, install and make true. Cuts PVC, DiBond, Kapa, acrylic, and glass; would chomp through correx. Struggles with aluminium over 1mm. I've also got a Javelin bench for fine detailed finishing work. Javelin cutters are true to less than 1mm/m. Couldn't work productively without the SteelTrak
A few years ago at UK Sign & Digital show, saw some knock off versions, for around 60% of the price. Can't vouch for the quality, but were from a reasonable size dealer. If you're only planning on Correx, then you could get one of the less robust KeenCut, or Fletcher machines designed for picture framers, which include a cutting head for Card stock - a wall mounted, T-squared Stanley knife. They go for a quarter the price of a SteelTrak second hand.
Assuming you've got a reasonably flat 8x4 bench, you could knock up a jig (basically a glorified T-square) in half an hour, and could rip through sheets in no time.