I have been building "cable boxes" and "DVRs" for a while now. If you tell people it is a PC, they don't seem to be interested.
I started out by making these "DVRs" that you don't have to pay monthly fees for friends and family at my cost (plus, I kept the rebate money $50-$100).
The word got around, friends of friends would ask what is that they have... and so on. But, I kept it strictly local. I don't want to pay for shipping and insurance, nor do I want to deal with remote support.
I mistakenly accepted an order from someone who is not in my driveable range. It is a pain to walk someone through the set up, and programming.
With local sales, I make people give me a 25% deposit to start the work, and then remainder is due at delivery. I tell them in advance to schedule their cable company to come the same day as delivery. Recently, people have been able to pick up CableCards them selves.
So, at delivery, I set everything up with ther Cable providers, and give them a tutorial, and leave them with printed instructions that I made.
Most of the installs from paying customers have been in "rich people's homes. People who have a home theater, and have multiple TV units with existing wired network.
There is an occasional "ghetto" cusotmer who wants everyting, but haggles about the price.
All of the units I install are locked in WMC, so that end user does not use it as PC. I had one customer ask me to unlock it, but I had him sign the warranty waver, since I did not want him to mess somehting up, and then ask me to come over and fix it. He did mess it up, but he had to pay me to come out and fix it.
I offer 1 year warranty, which people seem to be OK with.
I buy the same parts for every build, and just use an image from a known build to install everthing. It literally takes me about an hour to put one together and have it working. This way I can do it in the evenings, after work.
There is not enough income to quit my day job, but it is enough to support my hobbies. If I were making 5 of these per day, I could potentially quit my job.
By the way, Assasin, Dell pays $10 per Windows copy