Vienna to Budapest: Getting [much cheaper] MAV tickets outside of Hungary

Walk-up fares won't be cheaper, they'll be closer to the full fare that you see on OBB. I personally doubt that the extra savings from MAV is worth pursuing, thinking that third-party agencies would have extra fees and shipping or communication issues. You might want your friend in Germany to book the tickets (whether online or in person at a German train station) if it helps avoid a foreign transaction fee charged by your credit card.

The MAV website, along with other reports I've found online, explain that tickets purchased online may only be picked up at ticket machines within Hungary. Since none of us will be in Hungary before arriving on this train, we're not able to do this.

Domestic tickets purchased via the MAV website can be printed out at home. It is only international tickets that have to be picked up at a ticket machine in Hungary. Because you have an international ticket and your point of origin is outside Hungary, you're out of luck. I'm not familiar with any third-party agencies. Your best bet may be to work with your friend in Germany as they are at least physically closer to Hungary/Austria.

thank you for the replies.

one thing i thought of was to purchase a ticket from vienna to the first station in hungary on the OBB site, and then purchase a domestic ticket from that first hungarian station to the final destination in hungary on the MAV site.

my savings would be minimal, but if one were going further into hungary, this may be a useful technique.

Actually, that very technique is what I did when traveling in Hungary last year. In my case, there was not an international train (from Ukraine) at the time of day that we wanted to travel. I pre-purchased both a domestic Ukrainian ticket and a domestic Hungarian ticket online, both of which I was able to print before leaving. Then I had to only purchase the very short international connector from Chop, Ukraine to Zahony, Hungary in the Chop station.