Those appear to be very expensive from what retailers still claim to have them in stock.
I see out of stock notices on sellers that use to sell them much cheaper. One of the cheaper ones claim that it is only good for 20 cleanings.
Of course I do not know how much it would cost to migrate your tapes to newer storage.
It appears the drives were last sold in 2006.
It may be something similar to when the Compact Tape II stopped being manufactured. From my faulty memory, at the time manufacturing ceased, it was estimated that the manufacturer estimated they had over 10 years worth of in-stock inventory. That supply was exhausted in only a couple of years, as I suspect large users of TK drives made bulk purchases, and could not find new cartridges at any price.