I think you actually need a Business plan for that, as @luke mentions here.
I’m assuming that your build time is that long because you’re transforming images. I’d suggest to have a look at Netlify Large Media to drastically improve your build time.
Makes sense! You do not in fact need even a Pro plan to get more build time! If you’ll put a credit card onto your team’s billing page so we will be able to charge you for build minutes usage over the amount included on your team, and let me know which site or sites need up to 30 minutes to build, we can get that/those site(s) up to 30 minutes of time allocated per build.