Source: bought dozens of tickets across Canada, the USA, and England, over more than a decade, from presale to third party resale.
Ticketmaster are a total scum company. They essentially allow scalpers to use bots to buy up tickets, then take another cut when the scalpers "officially" resell them. This is usually limited to "fair market value" (if an event sells out quickly, prices go up) but they also sell on third party sites like ticketsales where there is no limit on price. Tickmaster is one of few concert ticket sellers and they basically have a stranglehold on the market since you often can't buy from the venue.
So the tickets you could buy now could be a couple things: prospective scalpers who know they'll get tickets in a presale, or a previous presale to a fan club or something. I'm pretty sure I've bought on a tm presale that wasn't listed on tm once before.
As for the pricing, tickets can range in price from $20 to thousands, depending on venue, seating, VIP, diamond, etc. I feel like the cheap nosebleeds in my history have usually been $50-100, compared to $100-200 for midrange, and $200+ for close range. The cheap seats will likely not cost $400 in the actual presale/sale. I suggest trying to get seats literally the minute the presale starts. Use a computer and a mobile if you can. I once used two work computers plus my phone to try to get tickets for a show with our moms but was met with slow loads/none available, when a coworker got though on her phone for me. Try every presale. Try again in the general sale if you don't succeed. Then pay out the nose to a scalper if it still doesn't work out and you really wanna go.
Sidenote: get as close as your wallet will allow. I've been in the back, middle, and front rail for hundreds of bands, at 500 person clubs to 80k festivals. The experience gets exponentially better the closer you are, in my experience and preference anyway. Check the perks of VIP if that's in your price range, they usually don't sell out as quickly and can be cheaper than worse resale seats. Soundcheck can be a fun time with a possibility of autographs, and the possibility of being front rail can be worth it alone as it makes the giant spectacle feel a bit more intimate when you can make eye contact with the performer, get a setlist from the stage after, etc. Sitting next to the sound booth will provide the absolute best quality sound in the venue. Also, buy quality ear plugs designed for concerts, not generic orange ones that cut out all the high frequencies. I like Loops and will never attend another show without something like them.
Regardless, I hope you both get to go, and enjoy the show!
Thank you so much for your thoughtful response. Couple questions. It seems Ticketmaster is the only way to get these tickets. Even on the Allstate Arena website it redirects to Ticketmaster so it appears they ARE the official licensed provider of these tickets, which sucks because you said they inflate the prices. But since theyre not scalping the tickets, theyre the main supplier of tickets, then they dont have a right to inflate the prices. Wouldnt bad bunny be upset If they did that?
Also, I have never seen someone wear ear plugs at a concert. What is their purpose?
Oh and what are presale codes? A lot of people are asking for them online. Can they only be used during pre order?