I havn't sold anything but have purchased thousands of photos & art over the years for the companies that I worked for. Some of the paintings (original oils) were up to $16,000 each & that was for full reproduction rights only, the artist kept the paintings and sold them for an addtl $18,000 with no repro rights. Iv've also paid as little as $60.00 for print reproducion rights for photography. As the original creator of the "art" you still own its' copyright even if you assign it to someone else UNLESS you are an employee doing art for a company or you agree to any terminology that deams the art as "work for hire". That translates into "this person was temporarily employed by us to do this art, therefore all rights are reserved by the company". Just be fair & the more work you sell & the better your stuff is regognized the higher price you can charge.