Here's a list I made a while ago of all the houses, their location, cost and the achievements needed to buy them: https://forums.elderscrollsonline.com/en/discussion/312685/achievements-required-for-houses-other-info
As a general rule of thumb smaller houses need easier achievements - like the ones for saving that particular town from whoever is attacking it at that moment. Bigger ones require you to complete an entire region and the manors require completing the entire alliance zone.