Hi Kevin, As a Shopify community member, it is really sad to know that you are looking to leave Shopify.
With respect to migration tool, LitExtension is a highly recommended tool in the eCommerce community to migrate from Shopify to Majento. Price stands at $149
It migrates products,customers and orders.
I must say that I havent tried the product myself. Am happy with Shopify :) But I hope LiteExtension works for you. Got questions? reply here. I will be glad to help
I've also experienced with data migration from Shopify to Magento.
And I highly recommend you use the product: Shopify to Magento data migration tool by LITEXTENSION. It supported me to convert all database from the first store to the target on Magento effectively, accurately and fast in just some clicks. Hope this helps!
I've also experienced the migration before and in your case, I highly recommend the product named Shopify to Magento Migration Tool by Litextension. When using it, I found it really reliable, effective, accurate and fast. With some simple clicks, you can complete your migration. Try it if you'd like to give it a thought