Digital Window Ltd., a joint venture of German publishing company Axel Springer AG and Swiss firm PubliGroupe SA,  has agreed to buy competitor Perfiliate Ltd., which operates Buy.at, from AOL Inc. just two years after the Internet company bought the marketing operation.

Financial terms of the deal were undisclosed, but it’s fair to say the price will be significantly less than the rumoured $150 million AOL paid in early 2008. London-based Digital Window Ltd., which runs a network of affiliate marketing sites  that guide customers to e-commerce sites in exchange for a cut of sales, hopes the acquisition will help form what the joint venture calls “Britain’s largest performance-based marketing group.”

AOL, which split from Time Warner Inc. late last year, were expecting their purchase of Buy.at to boost their Advertising.com business “serve merchant and retail advertisers with the industry’s most comprehensive set of e-commerce offerings.” The dial-up Internet pioneer of the ’90s has been trying to streamline and concentrate on building itself up as a content and advertising business, but the company’s efforts to increase advertising revenue have sputtered the past year. It runs dozens of Web sites, including popular tech blog Engadget and personal finance site WalletPop.

Formed in 2002, Buy.at is a global affiliate network that produces marketing campaigns for clients. More than 300 merchant brands use the platform to access 40,000 online publishers. Among its customers are U.K. telecom company O2, a unit of Telefonica SA, and Virgin Media Inc. Buy.at retains about 70 employees at offices in London and Newcastle.