Freelance Web Design

For a job requiring elements of design and functionality (i.e. theme and customized CMS or once-off db and simple front-end + graphic work) I'd charge around $2k as an amateur having only a little more experience than you (3-4 yrs).  For something more static/less flexible, I might go as low as $1k.  But these estimates make "averaged" assumption of the nature of the project and output expected.

For a more generalized estimate, guess how long it will take in days, then assume you'll work 10-hour days, double that product, and you'll have an estimate in man-hours that might actually be close.  Then multiply by what would a reasonable hourly rate if you got hired locally as a junior developer.  You should also note that your profitability (matching reasonable contract price to reasonable wage) depends highly upon your previous experience specifically with web design...not so much due to varying competence, but speed/productivity.