Since there's no way Rice ever comes close to selling out their stadium, I normally just buy my tickets when I get there. But the Alumni Association sent me this link to buy tickets from from our Athletic Department. Wait - $30 for General Admission?
I went to https://riceowls.com, and it has this link, which has GA tickets for $13. Huh? It isn't even Ticketmaster, it's fevo.com (never heard of it). Well, it does say "713 Community Heroes", and then clicking the ABOUT tab, it says "Rice University is set to celebrate 713 Community Heroes at Rice vs. North Texas game. Community Heroes can purchase up to 7 tickets at $13 for this game." So they're supposed to be for a special group?
I finally found the ticketmaster link: https://oss.ticketmaster.com/aps/rice/EN/buy/details/19FB1123. GA tickets are $20 there, and there are $30 reserved tickets which include the sections (110 & 111) which are usually the visitor sections. So maybe the ones you buy from NT aren't actually GA.
If you're inclined to buy online, you can support the Mean Green, or you can try to get $13 tickets. Or, you can just wait until you get there. I've found that you can sit in the visitors sections even with a GA ticket - I don't recall ever seeing any "Seat Nazis" at Rice Stadium.