Pricing & searching for logic board

Your iPad has no user-replaceable parts - and Apple will not supply components outside of its network of Apple Authorised Service Providers (AASPs). For devices that remain in hardware support, you can arrange for repair via an Apple Store or an Apple Authorised Service Provider (AASP):

Genius Bar Reservation and Apple Support Options - Apple

Apple also have a mail-in repair service:

iPad Service & Repair - Apple Support

You'll need to go through Apple Support directly. 1-800-MY-APPLE or use the Apple Support app on your iPhone or iPad.

This is correct. I mistakenly thought Self Repair was available for iPad as well.