Include the full item link in the generated RSS.

There's a "full" link available at https://meh.com/deals/<slug> which when unauthenticated is available a few places.  The one that seemed most likely to be reliable was the "meh." button's (others included the forum widget on the right and somewhere else lower on the page).  This has the added benefit of dropping you into the 'buy' light box once you log in.