I bought 10 of these sites about 6 months ago.
The sites look good and I was certainly happy with the end result.
In terms of revenue they produce - they make $50 a month total on Adsense and a few dollars a month on Amazon.
The reason I think the make such a small amount of money is content. I think Google values unique content alot higher than using autoblogging content.
So if your prepared to put in some extra work on the sites maybe you could make a little more = but they are not a get rich quick scheme.