Cost per mille requires only that the publisher make the advertising available on his or her website and display it to the page visitors in order to receive a commission. Pay per click requires one additional step in the conversion process to generate revenue for the publisher: A visitor must not only be made aware of the advertisement but must also click on the advertisement to visit the advertiser's website.
Contact the company directly. If you use a product or service and want to recommend it but you can’t find evidence of an affiliate program, consider approaching them and asking if they are willing to set one up (maybe with your help). Highlight your audience and the value of your recommendation. Explain that an affiliate program is simply rewarding happy customers (you!) for promoting, and they don’t have to pay until a sale is made.
If the answer to each of these questions is a resounding yes, rather than jumping to conclusions immediately, take time to research whether or not others are out there making a sustainable affiliate income from products and content in this niche. In a sense, competition is a good thing here—it'll help you validate your idea and prove that it's worth of building a business around.