Choose a server side language (PHP, Perl, Ruby, Python, C#.NET, VB.NET, etc). You can use any language you want, reading the feeds is nothing complicated -- downloading a file and parsing some text. The work will be in what you make with the data once you get it out of the feed.
Whatever way you go, make sure the expected payoff is more than the time you're going to invest learning how to do it. Is it worth building a whole store over picking a few products and advertising them on your site more directly?