Cooking, Food Education/Gastronomy & Lifestyle may seem loosely related. But they are all very different niches.
I love cooking. But for the life of me, I can never spend hours setting up a recipe blog and post studio quality pics of my dishes everyday. That is limited to wives of web designers who spend their entire day in the kitches, or large cooking outlets who pay women to achieve the same in a studio environment.
I am in the food education/gastronomy niche. I source my photos from istock or deposit photos here. Mainly because I don't need pictures of readymade, well-plated delicacies here, rather beautiful pics of their incredients.
Exhibit A -
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Exhibit D
I have built a forum based around this niche. And I am sure a wonderful app can be built around an aggregator in this niche.
I used to be in the lifestyle niche. But I sold the property (an iOS app targeted at men) about a year ago. The current owner has been working own porting it to android for a year now. Don't know why they don't have it yet. Bah! Some people..
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I'd be happy to answer some questions for you, to the best of my knowledge. However, I'd appreciate if you'd ask them publicly, so that others can benefit out of the same too.
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The most important factors here is testing. I've asked people to do this before as well - but people seem to reply on third party advice for some reason.
Set aside $1k for the site, if you're exploring a niche. Build out a basic version of what you envison and throw some Google traffic + Facebook traffic at it. The response you receive should get you a very good idea about how well your niche is going down with your target demographics. Spending on both PPC platforms will give you an idea of how well your site can do organically on search engines as well as through a social platform (in terms of conversions). Build a list. Get laid a lot. Build the next Yummly!
May the force be with you.