If I was going to be doing art type engraving, I think I'd look at V-carve. I've seen some really good outputs, much better than you would get from monkeying around for hours and days with dxf files and hand building a program.
I'd go and pick bottles for recycle or something, until I could afford the $$ In this day and time, if you can't do the work fast enough to keep the time cost down, you won't get much work, or you won't feel like doing it for pennies/hour return. So you need to spend a few dollars on software because that is essential to success.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)