I totally agree that it is an expensive way to buy miles if it is a domestic flight. In my case I need an additional 40,000 miles to get 2 business class return ticket to Australia. With those tickets currently at aroung $7000-8000 each I think boosting my miles for an additional $1000 to go from coach to business for such a long trip is worth it.

I am well aware of the credit card bonuses and E'trade etc etc. But I don't have the time to build that extra 40,000 with these methods.