I get your point as I started down this same path but I very much doubt you will make anything near the quality and consistency as the JTech laser for $100. I am VERY happy with what I bought and I would not change it for anything. As far as the software I am sure there are free ones out there but I am not against supporting those who write software. Spending $30-40 for software is not the end of the world.
Here is what I burnt today using the Laser Etch software. The smaller one (2″ wide) took 20 minutes and the larger one (4″ wide) took 40 minutes. I am still working out the lasing speed vs/ laser power.