Let me repeat that: Cost is not important.
What is important is ROI (Return on Investment).
When spending any money on a marketing campaign, you should consider the following:
- How much money you can you afford to spend?
- How soon will you see the return from that money?
- How much will that return be?
If you can spend the money (1), not go broke while you’re waiting for the return (2) and the result will be enough of a profit to make it worthwhile (3) then the cost of the campaign is not important.