Yes, but as with most combined-purpose machines, you get more value out of buying them together. Meanwhile, each gains some extra functionality from the others that it might not have on their own. The key is bringing all of them to light at good quality--perhaps with some enticing extras that other individual pieces wouldn't offer--and bring them out at a price low enough that people HAVE to snap them up.
If I were seriously looking for a high-capacity PVR and/or set-top DVD burner on my own, the PSX automatically comes into consideration. If the extras are desirable and the price not too burdensome...? Well then, that is a sale.