"The only solution I can think of is using an addon to parse chat. Ie: enter item you are selling and price into addon, addon sends a formatted message to chat, addon used by other players stores the message in local cache, you sort through cache to find item you want, and hitting the "buy" button puts you in touch with the selling player, while sending a chat message telling others' addon to delete the item from their listing.
In other words, an AH using an add-on instead of a native function that renders chat unusable for those that don't have it, and makes buying/selling impossible for those that don't have, making it a defacto requirement for participation in the economy and rendering the lack of a native system pointless. "
Does this sound viable?
Uses custom chat channel so as not to spam common chat channels. All users that use the add-on would collect the data and pass it on to players in other channels (/guild, etc).
Allows the player to post and browse items at any time while playing.
Downside: Does not fully make up for the lack of an AH.
Features could include;
Option to limit the amount of data stored to the last X number of days or hours.
Only broadcasts users list of items for sale upon logging in, changing the list, zone change, chat add, etc, with manual re-posting as well.
Faction only(?). Would have to see if the data could be sent across factions and if so whether it would be of any use (how to communicate?).
Once buyer has indicated a desire for the item the add-on preps the mail (with COD option auto checked) and waits for the seller to send it.
Future options would be to add sort options, "looking for" item announcement, min/max levels, and all the other standard AH features.
Too much to ask? If so, what would be needed in the game to make this work?