Did we get sucked into a bad deal?

[Rondell Staten]

Greetings, BP community.  The downtown Atlanta area is up and coming and we we're trying to catch the wave in the neighborhood. The property is close to schools and a new park that's being constructed that will become the largest in Atlanta. Properties all around it are going for over $100K and require a full rehab. We made the offer of $70K sight unseen based on the realtor's advice contingent to a walkthrough, etc. but were unable to find out what the rents were in the complex. When the offer was made, the seller's agent shared the rent of the current tenant is $670 (which seems very low). Based on that information, the numbers don't work but we figured we could add some value to justify higher rent. I did some more digging and found another property in the complex sold for $60K about a month ago and two before that for even less. I'd asked the realtor about the comps prior to making the offer and she assured me that the property is worth at least $80K. Anyway, now my concern is not just that we'd be paying too much but that the bank will not approve the loan amount based on the actual comps. I know that if this happens we have the option to renegotiate with the seller, pay the difference, or just walk away. Is this a terrible deal that we should run from or is there a way to salvage it without becoming a fool and his money? Thanks in advance for any advice.