I’m going with 23k.
I don’t believe more people buy from sources outside the AD. I’d guess it’s a 2:1 favoring purchases through the AD.
I disagree, here are my reasons (admittedly, some are very much anecdotal):
1) If you aren't a high donor, it doesn't make much sense to buy thru ISU (other than selling out the allotment to look good for future bowls, which was never a question). The ISU allotted tickets for this game seem even worse than those for the Liberty last year, and how many people (some of which donate quite bit) have expressed unhappiness with their tickets from last year?
2) Ticket City is the only 3rd party site I've seen publish sales figures, and their data says the Alamo is the best selling outside of NY6, and of those sales over 50% have come from the state of Iowa (only 4% from Washington).
3) My group of 7 bought through StubHub, and judging by the price differences on each side of the stadium, A LOT of other cyclones have done the same.
Go STATE, looking forward to being there with 30k+!