I have two websites that pertain to credit cards, one is
http://www.cardrewards.net which has a feed that the company automatically updates the apr's, annual fees etc, so the only time is designing your layout, and seo. The feed is free.
The other site
http://www.creditimes.com, I created ssi for the text and card art, and update manually. As far as time and maintenance, almost daily for the last year, but cost is still only the price of domain registration and hosting.
I can't even imagine what their advertising costs are, as they seem to bid on every possible credit, and finance term possible. But their type in domain must justify the expense.
You could build a site similar to creditcards.com with a feed for next to nothing, what you do with it afterwords, seo, ppc would determine the cost and time.
