Bill,
You said exactly what I was thinking. Great points.
Like Bill I will go ahead and be as honest about my opinion as I can. You may not like my answer but remember: You asked for it

.
Early in my career in the world of IT I can't tell you how many friends, relatives, and strangers wanted to ask me about their computer issues or look at their PC, or network for free. Early on, like many new to a career, I was happy to help for free to get the experience, but like anything else you get to a point where you need to ask yourself what value you give to your services. Be it working for someone else or working for yourself you need to understand the true value of your services and what approach you have to your customer relations. Some chose to take a hard line and ask that every minute be accounted for, while others may put much more work into a project than they actually get paid for. In the end it is a free market system. You choose which skills to offer by getting certain training, experience or education, and customers have a choice of who to use for certain services.
A great example of one way of doing things happened to me not too long ago. I got a flat tire on my truck so I put on the spare and headed to a tire shop. He took my flat and plugged the hole and took off my spare. He came and asked how long it was since I had a rotation and I told him it had been a long while so he went away and 15 minutes later he came back and told me he plugged my flat and thought the tires needed rotated so he went ahead and did that. I asked him how much and he said for me just to come back the next time I needed tires and he'd call it even. A week later I noticed my iwfes car needed some new tires so we went back and got them there and I plan on going back the next time I need tires.
The next time someone comes an asks you a question that eats up 15 minutes of your time or maybe you walk over to his T hanger to take a quick look at something you may want to remember that maybe the next time you are worried about where your next customer will come from he will walk in your hanger and ask for you to do an annual on his King Air. It's not going to happen every time but in a career that admittedly by many is hard to get steady work I would think that every opportunity to gain another customer would be welome.
In my careeer I run an Network Infrastructure group for a large company. In my department alone we spend about $4,000,000 every year in capital to sustain the services that we provide to our customers. How do we pay for it? Well, we allocate it out in the costs of our services. On a smaller scale it is the same for you. Maybe you need $2500 in education a year and you spent $10,000 on tools or materials that you expect to last you on average 5 years, and $1000 on material that will need to be replaced annualy such as manuals. So you can figure it out based on a full work load of 2080.
$2,500 annual recurring edcuation
$1,000 annual expenses
$2,000 tool expenses annualized over 5 years ($10,000/5)
$5,500 total annual expenses
2080 hours worked peryear
$2.64 your costs of expenses per hour worked
Many industries have to spend a lot of money on marketing just to get customers to walk in the door let alone purchase a product or service. In your case you have to spend a lot of money paying for tools and education. It is the cost of doing business. How many doctors, lawyers, etc get asked to give free advice by freinds, family, and strangers. I can assure you it is many. I don't think you have a unique situation here.
Ryan