What's my art worth?

boy-o-boy this topic is such a predicament. 

there's so many ways to charge for it, but yet, many clients don't want to pay even my low price for work. 
i don't charge too much... but i'm not making it big as a career, either. 
i have categorized myself as a hobbyist. not a professional. mostly because I know i haven't got any real professional work under my belt. (and it's super hard to come by too, as most people want you to be familiar with 8 programs that I've never even heard of and probably can't afford... that is of course, when you're trying to get a job as a game character designer or digital illustrator and such.)

you can charge by the square inch, too. but then the client may want you to work in a certain size. they will probably want the cheapest size too. idk, that way I've not found to be good when working in digital. 

you can charge hourly, but who's to say you didn't slack and spent some of those hours lazily. Clients are really confused with the whole hourly thing and I've found it to be unhelpful to explain it to them because they just want simple solid round price answers. If I start telling them about how much my supplies cost and everything, they tend to become uninterested and look for someone else who will do it cheaper. 

in fact, I have found that many people go to other people who are cheaper than I am (even though my prices are my lowest asking price--i don't haggle, really)
sometimes, people go to others who simply do "requests" which are free.  i don't think I am being paid what my art's worth, but nobody seems to want to pay more than that. 
it just seems really hard to make people understand that good art doesn't come cheap. i don't get commissions at all when i put my prices too high. most of the people I would technically be competing with are priced at around 25-30 dollars a drawing-fully colored. even though i know i spent 16 hours on my drawing or something, i've been charging a lot less than I should. 
i've recently raised my prices (about 2-3 weeks ago or so) because I felt i shouldn't work like a dog for almost nothing. 

i guess I should just post an hourly rate, too. It's very hard because I know commissions will not be as frequent if I do.

this leaves a lot for me to think about...