You can search Delaware County records fairly easily by using the county's on-line database. Search the web for "Delco Public Access" to get to the home page. Then use the "Real Estate & Tax Records" link to search by township & street name to determine the property owner's name, then use the "Recorder of Deeds" link to search by owner's name for most recent activity relating to that property.
The "Recorder of Deeds" information is usually updated more quickly than the "Real Estate & Tax Records" database. If you can't find details on the property you are interested in, it is possible that the deed has not yet been recorded by the new owner, which is often the lending institution which foreclosed on the property. Lenders who assume ownership of a property will often subsequently list the property for sale, so check with your real estate agent if you are interested in a particular property. Feel free to contact me if you have more questions. Good luck!