What is the cost to replace the charging port on my iPad? Seven?

Depends on where you are in the word and whether or not you have Apple Care+ and the actual model of iPad.

You can verify what model you have at the following link.

click here ➜ Identify your iPad model - Apple Support

For an actual 7th Generation iPad released in 2019 in the US:

$249 without Apple Care+

$49 if you have Apple Care+.

See the "How much will it cost" section in the following support document.

click here ➜ iPad Repair and Service - Apple Support

Typically, for any kind of iPad service, Apple does not repair but replaces with a factory refurbished model of exactly the same specs as your old one. That is not done in-store but at a centralized refurbishment facility. If you use Apple's ship-in/mail-in option, you save a day on each end over having an Apple retail store ship it.

What goes into an Apple refurbed iPad is here: Learn more about each refurbished iPad.

I needed battery service on my iPad and the replacement refurb was perfect i every way and is still going strong four years later..