Thanks for your info. Actually, I did not know about marketeer until you mentioned it.
And here is what I found with google:
marketeer 89,000
marketer 689,000
And both words are shown in my dictionary, and marketer looks like an "American English" , and marketeer is more like British English??
Both marketer.com and marketeer.com are registered but with no valid contents.
And there are both emarketer.com and emarketeer.com. The emarketer.com is a big marketing company as I read, and emarketeer.com is up for sale at buydomains.com now.