Commission piece penciled and inked by George Perez. The Spectre vs Eclipso
Thanks for sending your George Perez artwork in for appraisal.
Commissioned pieces are not published work, so while they are undoubtedly cool -- especially if the characters are meaningful to you -- they are not as valuable as published artwork by the same artist.
The highest sale I found for a commissioned piece by Perez was $400 for a Wolverine. A much more popular character.
However, your piece is very detailed, and for that reason I think it might also sell for around $400.