Don't get discouraged but it is very hard to do what you are wanting to do.

Doing the programming has inherent problems that you will have to deal with like wrong codes, sync issues, anything. Then they email you, wait for you to do changes (time difference) reload programming, test. Extra work you want paid for, they already paid, blame you, client getting upset, installer getting upset. Lots of things go wrong.

I would look into making your website better suited for selling GUI's or pre-made pages that can be downloaded easily and paid for with a credit card.

Example, I buy your DTV pages for $4.99 load in my commands into the pages in five minutes and I'm done and happy that I didn't spend a hour making all the graphics.

Just a thought.