Unfortunately, those three exams are kind of unavoidably expensive. The Holter not so much, but the others require skilled personnel and expensive machinery, as well as a radiologist to view the results. That tends to make things add up quickly.
If you could shop around and try to find a hospital based clinic, rather than a private practice, that should save you some cash. Hospital based practices must be not-for-profit to accept government funds.
What sort of ectopic heartbeat do you have?