Top agencies earn a fortune, but it's all relative. A company that turns over £2m p/a might have 20 staff... Either way, have a look at the NMA top 50 marketing agencies (you need to register) that list is based on turnover ( most PPC agencies charge between 10% - 20% for managing a decent campaign. nmatop100.co.uk/Registration.aspx?ReturnUrl=%2fentryListing.aspx%3fcat%3dcompanyType%26subCat%3d1%26outputNumber%3d50%26name%3dmarket%26UnrankedCompanyType%3dMarketing%26showKeyImage%3dfalse&cat=companyType&subCat=1&outputNumber=50&name=market&UnrankedCompanyType=Marketing&showKeyImage=false (Sorry, no live links)