Axminster?
Seriously, (a) their customer service is excellent, (b) they do carry a lot of spares, (c) there are many interchangeable parts with the TS200, and I think the sliding carriage system is one such.
It's also common-ish to other similar saws. If you look for images on Google you should see a lot with a similar rail - chances are they will either fit straight off, or can be made to. The arrangement is derived from the Kity 419 (at least it is on the old TS200), including an awkward bodge to get the heights to align properly. It shouldn't be too hard to make up brackets yourself if you can get the rail and carriage, and those are definitely common to a range of other brands.
Bear in mind too that the sliding carriages are not as wonderful as they seem. It's a small saw physically, and the track isn't very long. A proper panel saw is a very different beast. And if you fit a track in a small workshop, it gets in the way all the time it's not in use!