Where did the buy.at name come from?
Long before "buy.at" became an official affiliate network, it was a redirection service known as rename.com (based around .at domains).
This redirection service was used by Perfiliate Technologies - a company that supplied sites for charity and non-profit organizations. Perfiliate created each of these nonprofit sites using short links beginning with "www.buy.at/" and ending with the charity name, such as "www.buy.at/Norwichcity".
What's with the .at?
Perfiliate needed a series of URLs to create these charity sites, and the "buy.at/(charityname)" served as a call to action.
Also, the ".at" is an Austrian domain. Why did Perfiliate use Austrian domains? At the time there were many available domains in Austria with english words.
Then what?
Perfiliate Technologies rapidly expanded to provide affiliate marketing solutions for many of the leading names in the UK including AA, BT, Lloyds TSB, M&S, T-Mobile, Sky. In 2002, the company officially launched the buy.at affiliate network - which then expanded into the US in early 2008.