Chris,
Don't over complicate things. You really only need to know 3 or 4 things. 1. What can you get it for? 2. What is it worth TODAY? 3. What are the repairs? 3. What can I really rent it for? Can you get financed or will the bank finance it to get it off the books?
Do your research and then you can answer whether it is a good deal or not. A sales figure of 2006 is worthless. You have to talk to find out what the bank is willing to sell it for. They may or may not be willing to deal depending on how long they have had it. To figure out the rents, check the paper for that area, talk to 3 realtors, a property management company, etc. You have to ask more than one to make sure the one you asked isn't smoking crack and giving you bad numbers.
To find the value, also check with realtors, drive the neighborhood; check the paper for similar homes, etc. Again, you want more than one opinion of value as one or more of those you ask may be delusional.
To find the repairs, walk through with a good contractor, if the other numbers warrant going this far, assuming you are not a contractor and can do the estimated repairs yourself. These are most of the things you need before truly deciding if it is a good deal.
Until you know these numbers, you don't know if you have a good deal. When in doubt, be conservative in your estimates. After you answer these questions, you can use the 50% rule previously mentioned and well discussed to objectively look at the numbers and decide if you should move forward.
Good luck
Mike C