Create an alert to track pet listings region wide:

{
    "region": "US",
    "user_auctions": [
        {"realmID": 1263, "petID": 3390 ,"price": 25000000},
        {"realmID": 25, "petID": 3390 ,"price": 25000000},
        {"realmID": 52, "petID": 3390 ,"price": 33000000},
        {"realmID": 52, "petID": 3541 ,"price": 93000000}
    ]
}

To do this we are going to need to have something to get / update pet listing prices for a user whenever they open the AH window on any realm. It will delete and replace old records for a realm whenever you view the AH again.

This will track the petID, realmID and listing price in copper.

The only other field is the region.