'To expensive to be owned' Not really sure what you mean - The units themselves will be about the same price as the other 350s, 450s etc. there isn't anything special about them, they were just bought when interest rates were high so loans were expensive so the cost of leasing them is pretty high, similar to the 379s procured at about the same time and are similar in being standard 25kV 100mph (well until the 350s got upgraded) 20m EMUs which are incredibly similar to trains made a couple years prior. Porterbrook could probably re-negotiate a lower interest deal, assuming they haven't already paid most of it of, but it would probably need a longer lease.