What can substitute the official table? It feels extortionately overpriced at $600 USD.
An overbed table like in the hospitals seem to be at a lower price than the official table. Search for overbed tables in amazon and you will find them less than 100 dollars. You can also use this when you are in bed.
Edit: If that does not work for you. Then a search for "laptop desk for couch" in amazon will yield something like this: