I do this full time, and I've submitted a freesite almost every day since I started back in March. (Sometimes it's just not possible to do it every day, hence the "almost")
So far I have around 150 freesites built & submitted. Most are listed
here if you want to take a peek.
I'm quite pleased with my sales overall, and although I don't make $1000/month yet, but my numbers rise each month and it looks like if I keep building & submitting then it won't be long before I pass that.
I have a hub/fake LL thing
here and a spin-off webcam site
here. There are also two or three little sites linked from those which are part of my little tiny weensy network.
My advice would be to vary the niches, build many more sites, and stop worrying about your sales at the moment. 13 freesites is nowhere near enough to judge much at all, so keep on building. Surf Linklists and look at other people's freesites to pick up tips on what sales text to use, colours to use, layouts etc. Look for freesites that link to hubs and poke around them a bit.
Build, learn, tweak, build, learn, tweak, build.....etc
Good luck!
