Artwork appraisal is available through Appraisers.org and ValueMyStuff.com, as of 2015. Appraisers.org offers a tool to find nearby appraisers, while ValueMyStuff.com offers online appraisals. Alternatively, search for an artwork on ArtValue.com to see selling prices for recent auctions of that piece.
To use the tool on Appraisers.org, visit the site's homepage, and click Find An Appraiser. Fill out the form with the necessary information, and perform a search.
For an online appraisal through ValueMyStuff.com, visit the site's homepage, and place the cursor over Categories. On the drop-down menu that appears, click one of the artwork categories, and then proceed through the appraisal process.
Factors that affect the value of an artwork include the artist, the history of the piece and its condition. A professional appraisal is often necessary to determine a piece's value, as most people don't have the expertise to appraise a piece themselves.