Blizzard is raising the level cap with Cataclysm to 85. This means most level 80 items and equipment will become obsolete. Items and equipment is a deciding factor for people buying accounts and as such, the expansion is bad news for you. Of course, if your account contains several level 80 characters, it will remain more attractive to most buyers.

The expansion is not all bad news. History has proved new expansions to attract both new and returning players. Some players may not want to start up from scratch, and this provides sellers with an opportunity.

As always, I recommend you read my book before you throw yourself and your account on the market.