"As an artist I have lost some clients due to the economy here in Atlanta, Georgia. I used to sell by time and material spent but that doesn't work. Right now I have a blank canvas that a client gave me to do a portrait, it's 11" x 24". The client is trying to low ball me. Any help?"It is really tough when money is tight and fewer people are willing to spend it on art, because we've still got to earn an income from somewhere, somehow. Some buyers will try to exploit this and your choices are to suck it up (you're desperate for the money) or say "this is what that size portrait costs if I paint it" and stand your ground (you're desperate but not at any price).
Try to avoid getting defensive about your prices, or bothering to explain why they are what they are. If they're insistent, remind them (gently) that they came to you. There are other people who know what your work is worth and appreciate it (even if you know they're not beating down the door right at the moment).
Artist Melissa Dinwiddie has an excellent article on this, 5 Art Pricing Lessons I Learned the Hard Way, including the comment: "Some money is too expensive." If the price ends up making you hate the painting of the portrait, resenting it, then it's money that's too expensive.