Math isn't as important as good sales pitches to most people.
My question to you is why would you, as a buyer, pay any real estate commissions anyway, when usually they are paid by the seller? If you are concerned about paying the taxes over a 30 year period, maybe you could have your real estate agent negotiate the offer on your behalf with that scenario in mind, which could put you in a better position when you do your taxes by incurring some real estate expenses at purchase. Of course speak to a qualified accountant first - not all accountants are created equally either. Make sure you speak to one that specializes in real estate and/or at least owns investment property themselves.
Good luck to you!