I think your earnings claims for the sites your building is somewhat overstated $500 a month per site seems pretty unrealistic ... there are just so many variables that go into the selection - and not every site built is successful ... anyway if I had a Sales Thread I would probably have to say its possible too .. that's just part of selling something.
Sorry but you're saying that I'm lying to make sales so I'm not going to let that slide.
Making money with SEO is a numbers game. The more keywords you rank for, the more money you make. You should know that by now.
The $300-$500 estimate was for the authority sites which target 20 keywords, 10 with 590-880 searches and 10 with 1000-1900 searches (all numbers are exact US local searches).
In my experience you'll make a minimum of $20 for each keyword with 1000 searches. Some keywords for these authority sites have 1900, 1600, 1300, but let's just got with 1000 even so we have round numbers.
10 keywords with 1000 searches = $200 per month.
Likewise, 500 searches will get about $10 per month. Sure, the keywords will have 590, 720 and 880 searches but 500 gets us a more even number.
10 keywords with 500 searches = $100 per month.
So if I only made sites with 500 and 1000 searches keywords you'd be looking at a minimum of $300 per month. Add in the higher search volumes and long tail keywords and $500 is a closer estimate. Keep in mind, this is after the SEO work is done.
The only variable is whether or not people do the off site SEO. If you see a flaw in my math let me know.