A lot goes into a custom website. That is why they look so good! And unlike cloud based sites, you own and control your site and data.
For basic sites without a shop or highly configurable plugins, you should budget $1200.
If you have a shop, it will depend on how many products you have, how complex your products are, and if you want me to add them. But if you are adding your products or do not have many, it will cost around $2000.
If you have a lot of products to migrate from another site, you will need to add the cost of migration. I recently built and migrated two websites with many products. The cost for each was very close to $5000.
If you want me to configure your SEO, that will be more. But totally worth it!