http://thepiratebay.org/torrent/6814878/Skyrim_Esbern_Voice_Fix.rar
Sup bitches. almost certainly works on legit as well as torrented, it's literally just the sound files for the char, I recommend copying them over JUST in case, it's a game breaking bug (for the main quest anyway, even if you get around it he plays a part later on)
(do it even if you don't think you'll bug, you'll need it)
If you don't have it, download Oblivion Mod Manager and install.
Find your skyrim's voicesextra.bsa and open with oblivion mod manager (using the utilities button - BSA browser - Extract all once you find the file located in data of Skyrim)
Extract it into skyrims Data folder. You don't have to drop it into a sub folder.
Once its done, start it up and enjoy not having that bug.
No guarantees it will work for everyone, but I was forever stuck at the negotiation with esbern and this fixed it.
(hello to everyone googling for help and coming across this !)