I think it is debatable as to what the biggest hurdle is in completing a set of 1971 Topps:
1. The cost of the big name stars [Willie Mays, Hank Aaron, etc...]
2. The scarcity of the higher numbered cards
Either way, I can cross two cards off the first problem from the list. I got these from the "90% off Beckett value" box at the "I saw Ernie Banks" card show from a few weeks ago.
#26 Bert Blyleven
#530 Carl Yastrzemski