A neat little company is Miller Engineering, which sells aftermarket discs of reportedly far, far better quality than the ones that come with Sony's: https://microstru.com/collections/star-discs. Their site also offers an extensive of the various home planetarium alternatives.

I've always wondered what is in these things that makes them worth $200. As far as I can tell, thehy're basically just a light bulb, a little motor that can slowly turn a slide disc, and some lenses. It leaves me wondering whether there's some aspect of its construction that makes it harder to construct. Something about the optics, perhaps? Do they need to be of especially high quality?