I think you are seeing what so many people have learned through the years of Facebook advertising: when people are on Facebook, their "mental state" is "goofing off, catching up with friends, and just blowing off steam". What you are advertising is <i>work</i> - which is always going to be hard for your audience to switch back into. Advertisers like Coca-Cola, Budweiser, Crown Royal - those are advertising "goofing off, catching up with friends, and just blowing off steam" thus their CTR/effectiveness is going to always be massively higher than "work" related ads: they are matching the mindset of the audience. When those companies advertise in another medium ("Fortune" magazine, for example), they will certainly use different ads - a different message, more sophisticated, older models, etc.<p>As an advertiser, you need to go where your market is <i>and you need to be there when they are actively trying to work</i>. Your sellers are most certainly in Google searching, searching, searching for this and that. Find out what they are searching for, and market to that need. Go to Adwords and find out what people are searching for when they use the term "ebay store", or "ebay seller's" or other prefixes that your market would use. For example, someone searching for "ebay fee calculator" is probably a seller - so buy that keyword and craft ads/landing pages around it. There are tons more...