Ah – always the hairy question 🙂 I price my work on a job to job basis, and I I generally do not charge an hourly rate. I take the following into consideration:
• The size of the job (ie. how many images are needed?)
• The complexity of the job
• What will the illustration be used for? A once-off magazine article, or an advertising campaign?
• The size of the client
• The size of the budget
• The geographic regions it will be used in
• I usually quote on a one time usage, or licencing for a limited amount of time (ie. 12 – 36 months) .
Please seek advice before entering into full copyright transfer agreements; handy sources of information can be found in the Graphic Artists Guild handbook