估价depends on all the data you give to them. if you give them that your house is small, everything you have were using the cheapest material, plus close to hydrant(in case of fire,easy to save your house) or you have alarm system(in case of someone break your house). It will help to lower your 估价. the problem is what kliu said if it is something happens to your house, you wont get what you want, you will get the cheapest thing.
two more things could help lower your premium
1, sometimes they ask you to have sewer coverage in case of basement flood.(most of the time you dont need it especially your basement is not finished and some basements have pump to drain the water out)
you dont have to pay that.
2, some companies may include household insurance, you can ask them lower that too(that is for your furniture, jewellery, food, appliances,clothes etc)
so if you worry something happens someday, you can get better reward if you pay more now. otherwise you know it.