According to a discussion I had here previously with a Kagi user, when they go out of beta they plan to offer a $10/month plan with a quota of 20 searches per day (and $0.015 per each additional search), and an unlimited plan for $20-30/month. Additionally, every time you change something related to your search query (such as clicking "Images", changing the sort order, applying filters, or blocking a website) counts as an additional search, so you could go through your quota pretty fast.

Apparently all of this is to offset the costs from paying Google and Bing to run searches for them (the site basically takes results from Google and Bing and then combines them together with their own special sauce) but with a pricing model like this it seems like Kagi will remain a niche tool solely used by the wealthy.