I own a Seafood Processing Company. We do production cutting, so sharp knives are essential for a good yield.
You can find some cheaper alternatives from DMT, but the extra upfront cost will save you a lot in the long run.
Whetstone's are decent, but the learning curve on these diamonds is much lower and you'll get a far superior edge with less than perfect technique.
Much lower learning curve than a whetstone. Plus, it will last you much longer if you take care of it. Especially if your knives are made from a softer steel. This will get them razor sharp.