You could add a disclaimer to your sale like :
Disclaimer: By bidding on, inquiring about, or viewing this auction you are stating that you are in NO way affiliated with Blizzard Entertainment, ESA - Entertainment Software Association, or any associated entity. World of Warcraft is a trademark of Blizzard Entertainment. All characters, items, gold pieces, or other intellectual property in World of Warcraft are the sole property of Blizzard Entertainment. This auction is not for the ownership of their intellectual property but rather for the time spent working on this character and acquiring items. All references to 'the character' are indicative of my time spent on leveling the aforementioned character. All characters, items, in-game currency, and anything else associated with this auction will remain the property of Blizzard Entertainment. According to the World of Warcraft EULA section 3.b: B. You may permanently transfer ownership of the Game and all parts thereof, and all of your rights and obligations under the License Agreement, to another by physically transferring the CD-ROM, all original packaging, and all Manuals or other documentation associated with the Game, and by removing from all of your home or personal computers and destroying any remaining materials concerning the Game in your possession or control, provided the recipient agrees to the terms of this License Agreement. The transferor (i.e., you), and not the Licensor, agrees to be solely responsible for any taxes, fees, charges, duties, withholdings, assessments, and the like, together with any interest, penalties, and additions imposed in connection with such transfer.
http://www.worldofwarcraft.com/legal/eula.html Disclaimer: You are bidding on my time leveling for this account. Said account remains the property of Blizzard. You will not 'OWN' the account, for it belongs to Blizzard. The only thing you are bidding on is the time I have invested into the account. All characters, items, in-game currency, and anything else associated with this auction will remain the property of Blizzard. By bidding on, inquiring about, or viewing this auction you are stating that you are in NO way affiliated with Blizzard Entertainment or any associated entity. World of Warcraft is a trademark of Blizzard Entertainment. All characters, items, gold pieces, or other intellectual property in World of Warcraft are the sole property of Blizzard Entertainment. This auction is not for the ownership of their intellectual property but rather for the time spent working on these characters and acquiring items. Before bidding on my auction you must read and agree to Blizzard's EULA located at:
http://www.worldofwarcraft.com/legal/eula.html All title, ownership rights, and intellectual property rights in and to World of Warcraft are owned by Blizzard Entertainment and its licensors. This auction is not for said rights or intellectual property but is a compensation for time and effort invested personally outside the game. All items related in this auction will remain the sole property of Blizzard Entertainment. By viewing OR bidding on this account you assert that you are in no way affiliated or employed with Blizzard Entertainment.Please note, I am not selling these characters, as the EULA of World Of Warcraft states that all characters are the intellectual property of Blizzard Entertainment. I am simply charging for the time and effort put into building these characters. The winning bidder will receive only the corresponding login and password used to enter the account. Because these codes were created by me and independent of any Blizzard Entertainment involvement, Blizzard Entertainment and all agents acting on their behalf have no right to sanction my selling of it nor do they have any right to prevent me from charging a buyer for the time it took me to produce it. Again, for those of you who may not understand: This auction does not violate any of Ebay's policies. This account is sold as is; everything I say about this account is what you will receive. If you are an employee of Blizzard Entertainment or acting as an agent on their behalf, you may not bid on this item and by bidding on this character you are stating that you are in no way associated with Blizzard Entertainment. World Of Warcraft is a trademark of Blizzard Entertainment. All characters, items and game currency are the property of Blizzard Entertainment.
and it becomes from illegal to debatable =)