If you assume that the servers only retain data for one month, then the server costs are cut by a factor of 12 and you end with €168M/12=€14M (roughly $18M). And a total cost of $22M.
Additionally the posting assumes that all the data is stored, that is a lot of cat videos. With decent preprocessing you can probably cut the data rate by a rather large factor ( I would assume at least 100, since you do not need to store warez or the NYT homepage.) Then to do the opposite estimate, by assuming that the system is CPU bound, one needs hardware to process 120 GB/s. With roughly $10M you can then buy a few thousand machines, and your PRISM software needs to handle something like ~50 MB/s per machine. ( Which may or may not be a reasonable data rate, depending on the sophistication of the algorithms, and how much can be discarded very easily.)
Additionally the posting assumes that all the data is stored, that is a lot of cat videos. With decent preprocessing you can probably cut the data rate by a rather large factor ( I would assume at least 100, since you do not need to store warez or the NYT homepage.) Then to do the opposite estimate, by assuming that the system is CPU bound, one needs hardware to process 120 GB/s. With roughly $10M you can then buy a few thousand machines, and your PRISM software needs to handle something like ~50 MB/s per machine. ( Which may or may not be a reasonable data rate, depending on the sophistication of the algorithms, and how much can be discarded very easily.)