If you're a bard or enchanter, you can cast some form of Alliance on Corun Finisc and the druid guild merchants will align to a faction good enough to sell to. This is a good trick because you can't cast alliance on any of the GMs or merchants themselves, which make up most of the faction.
Edit: You can also fix faction with the rangers and general merchants by casting Alliance on Merdan Fleetfoot.
Edited, Feb 8th 2011 5:17am by Teyeni