AOL has acquired buy.at, a leading affiliate marketing network backed by VC house DFJ Esprit, reports TechCrunch UK. Financial terms of the deal were not disclosed, but well-placed sources say the deal is worth in the region of $150 million (£75 million). Although launched in the UK in 2002, buy.at now has a much bigger US operation, which is what attracted AOL’s interest. buy.at will now operate as a wholly-owned business unit of Advertising.com, part of AOL’s Platform-A organization, to which it added four other companies in the last year including Tacoda, AdTech, Third Screen Media and Quigo. Unlike previous deals which were more about ad serving, the buy.at deal is about getting closer relationships with retailers. AOL is understood to have tried to buy another affiliate network, Tradedoubler, a year ago but the deal foundered with the latter’s shareholders, who couldn’t agree on price.