Most of the photos on the site linked above seem to be taken from http://unsplash.com (I am using some of them in my designs already) - maybe you can find additional content (over and above unsplash) to justify the cost of the service?
Weekly Snaps sends 10 images which are 100% royalty free to your inbox every week. We have done the due diligence on all images and you are free to use them however you please. We curate your weekly packages and you receive a free sample pack!
Zendesk
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Theseus
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Domino Spot