Worth buying this waterstone?

I found this combianation waterstone on ebay LINK and i was just wondering if it would be worthwhile getting it as a starter stone, i have a couple of knives both for bushcraft and cooking that i would like to keep "razor sharp". Currently working to a budget so i don't really want to be going out and spending £100 on a full set and thought this would be a good way to start and thought i would get the opinion of the guys here.
 

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