Beyond the Philly sheriff's links I gave some time ago, the only advise I have is to physically research the properties at the public records. You can find out if their are additional liens on the property.
As for pricing, you would need to contract the service of a real estate agent (that is using only one agent who would be willing to help). They would give you what you could get if the home was fully updated and good to go. Once you have that, you need to subtract the possible sell price from the sale. For instance: Market value could be $200K minus the $100K price at the sheriff sale equals $100K. This would leave plenty of room to spend your own money to fix the property, sell and retain a decent profit.
If the home would be worth $200K and it would cost you $175K to buy, then it probably would not be worth your time.