Are there some services that could act as middleware between NS and the client's system to keep the client on a lower tier?

I am confused, but why is this related to having a lower tier?

As far as I understand from our sales team, Oracle has charges on the number of records, right?

I see, so what you’re looking for is an additional database before data gets sent into NetSuite? What do you mean by middleware?

I mentioned it in the thread below this one.

For example, in a shipping company, the middleware could save all the data of shipments, and push to NS only the journals that the finance team cares about.

it’s my first time to hear this use case to be honest, the most common is to have NetSuite as the main storage, and manipulate the data through a BI tool, let’s wait to hear what the other professionals say

Check this thread https://netsuiteprofessionals.slack.com/archives/C298P0BCK/p1667944629635869