So there is a change to what you already did - we will now have all data in tab delimited CSV files, so we should not have problem any more with parsing huge files. Below are links to the files so you get an idea what we will be working with. Also there is going to be a unique identifier for all 4 files, so we will avoid any misunderstandings with matching data from those files:
1. [url removed, login to view]
This is basically a merged file of all wheel manufacturers - it's the application list that you created before, so you would need to adjust the importing to take data from this csv instead of the excel
2. [url removed, login to view]
Here we don't have any sample data, but it should give you an idea of the structure - it's very simple, one column is Part number and second one is price
3. [url removed, login to view]
this is info about the stock availability of the wheel directly in the factory. Contains PN (part number) and stock number
4. [url removed, login to view]
Similar to previous, but this is info about the stock availability of the wheel in our own warehouse.
So basically we need to store both stock infos. Based on this we will be able to show on the store frontend if the wheel is available right away or in e.g. 3 days.
It might also happen that since the price csv is updated more often than the application list, that we will have price with PN that does not exist in the application list. But we should import the price anyway since the PN might appear at some point later. SO we should store it.
5. import db of existing customers
we have a db of our existing cusomters in a mysql table with many custom fields (that will also need to show up in the front end), e.g. company owner name, bank account number, owner phone number... I am attaching a table structure dump to give you an idea.