Hi Ken, when you say pre-foreclosure I am assuming that you are interested in properties that have not yet been actually foreclosed. Technically, only properties that have no notice of default are truly pre-foreclosure. However, I am assuming you want to find properties that are already in foreclosure, but not yet scheduled for auction. I know that's a lot of assuming, but I am just trying to narrow down the question.
You can ask a title company to provide you with weekly foreclosure lists. There are usually three lists (those that just had the notice of default recorded, the properties for which the trustee sale has been set and those that are already bank owned). I am talking about a trustee sale because I am in CA where properties are not judicially foreclosed (in most cases). Since you are in Harrisburg, the foreclosure procedures may very well be different (I gathered that from you mentioning judicial sales in your question). If you are in a state where banks have to go through a judicial foreclosure process involving the courts, you'll most likely have more time to make offers than you'd have in CA (the whole process can take as little as 120 days.
I hope this helps. Good luck to you.