So it may be the realtor's mistake

If you sue the seller, you need to prove the seller fraud (Know the truth while telling something not trus). Mostly the listing agent copy from county record.

If you sue the Realtor, you may need to prove that the realtor misleading you. Like told you that that is what you expected to pay. If the Realor just pass the listing info to you (like most time I do). The Realtor has no mistake.

When you buy a house, it is your duty to ask questions.