Book cover design cost depends on the number of concepts and revisions, whether custom illustration or licensed imagery is needed, and whether you require ebook, paperback and hardback versions. Ask for the exact final file formats and usage rights in writing.
Ebook versus print
An ebook normally needs a front cover, while print editions require a full wrap with spine and back cover sized to the final trim, page count and printer specification.
Image and font licensing
Confirm whether third-party image or font licences are included and whether any restrictions apply to print runs or advertising use.
Revision scope
The proposal should state how many concept and revision rounds are included so the approval process is clear.