I don't know how much experience you have with the foreclosure process, and I certainly don't know the details of the exact foreclosure sale you are anticipating--
BUT--- be aware that the foreclosing lender will almost certainly bid the full amount they are owed by the defaulting borrower and that is way more than the remaining principal on the loan. The whys of that are multiple and no need to go into it in detail. Also, that amount is almost never less than the fair market value of the house on that day.
At least in Pennsylvania this appears to commonly not be the case. I pay attention to foreclosure sales because I think it's fun (I'm a weird dude), and take a look at this link, then sort by "Disposition" and search for "3rd party". You'll see a non-negligible portion of properties are sold for less than the balance. Not tons, but it does happen.
I dunno.. 11 third party sales out 388 cases (~3.5%) is closer to 'almost never' than 'commonly' to me, but they are both squishy phrases, so...
And I admit I don't know Pennsylvania court procedures. Never even got a traffic ticket there. As a general observation, I'd caution that not all judicial sales are the result of foreclosure by a lending institution so, if I really wanted to know, I'd look over those 11 sales to figure what is going on with them and what, if anything, they have in common.
I have been around the courthouse quite a bit in four or five southwestern states over the years and I'd stick by 'almost always' as a fair description of the times lending institutions protect themselves by bidding the judgement in a foreclosure that goes all the way to sale. As I hinted, it doesn't bother them if someone wants to bid more but it's the rare foreclosed house that is worth much more, because the ones that are typically sell some other way before the auction.
Not always-- just almost always.