Besides paying $2600/month for an AP news feed (500 articles/day), what other services can I look at for ingesting high volumes of content (completely automated)?
Setting up a forum that does not require registration and letting the spammers run riot works. The quality of posts is low but they do generate a lot of page views.
But on a more serious level, what you need to do is investigate is a technique known as ‘Scraping’. So even if a site has no api you can still extract its content, of course this practice of content thieving is universally frowned upon and you may find getting help difficult.