If you are going to consider your prices retail, then you can just charge by the line, for instance $10.00 per line of text, for example a name, 3 words at max. If you consider your pricing wholesale, then your looking at more like $4.00. The price per stitch your quoting is generally for designs rather than lines of text. If you want to sell designs then you will have to get software like Embird so you will know the exact stitch count.