I will fly (Indiana -- California), and one option is to take the cats
as "checked luggage". Problem is that most airlines only accept 2
carriers, and do not allow 2 pets/carrier.

Another option is to ship the cats separately as air cargo, but I'm not
sure how expensive that can be.

A pet moving company not an option because they're too expensive.

If anyone has any suggestions or tips, I'd be very grateful.

Thanks!