"Put up a site about a profitable niche, do some basic SEO, and bam! presto! Instant $50/month!" I've done this but the 10 page site brings it a little less, ab

"Put up a site about a profitable niche, do some basic SEO, and bam! presto! Instant $50/month!" I've done this but the 10 page site brings it a little less, about 30 - 40USD / month. No adwords, wrote the content myself, only one or two incoming links. If your niche / keywords are specific enough you'll rank in the top 5 without many problems. Keep in mind that since the content is very specific and does take some time to write (research, ...) knocking out 100 or even 10 sites like this would be quite hard work.