Each domain extension is run by a different domain registry. Thus, prices vary between domain extensions since each domain registry sets its own pricing and rules for their specific domain extension.
Domain names are a very low margin business. Most of your domain registration fees go directly to the domain registry rather than to us. We make money on other products and services we sell.
Registries also routinely increase their pricing (yearly these days, at different times throughout the year). We absorb these price increases when we can. However, given our low margins, as domain registries increase their prices, our prices must increase as well. Our domain pricing continues to be among the lowest and highly competitive with no hidden fees.
A full list of our domain extensions and pricing can be found at: Domain Extensions.
ICANN also charges domain registrars like Misk.com a fee for each domain registration/renewal. Most other domain registrars don't include ICANN fees in their up front domain pricing. Instead, they show it as a hidden fee during checkout. However, our domain pricing is always inclusive of all ICANN fees.