I am not an expert on early percussion muskets like these, although I tend to agree that they're probably made by local gunsmiths. There are historians that specialize in these guns, and for a historical appraisal I would turn to the National Muzzle Loading Rifle Association for advice. They can put you in touch with the experts, including those who have a strong familiarity with the Pennsylvania gunmaking vernaculars.
Appraisals of the value of any artifact like this are tricky because the market for these sorts of things fluctuates pretty wildly. Two determined bidders at an auction can artificially inflate the value of guns like this by several magnitudes, and in the next auction the same gun may go for half of its perceived value because there didn't happen to be any percussion fans in the audience. Point being, be wary of any specific dollar values provided to you. The best barometer of value is to look at what comparable guns are selling for.
In terms of restoration: please don't. These guns appear to be in their (mostly) original condition, and they will only ever be original once. The patina of age on the brass parts takes many decades to form, and the wood probably wears its original varnishes. I see evidence of what might be some contemporary repairs (in particular is a round headed screw on one of the lock plates), but at this point it's part of the gun's history and best left alone.
You will find a lot of advice on the internet and in forums like this about how to do all manner of cleaning and restoration and repair and anything else a person could want to do to an antique gun. This advice runs the gamut from excellent to terrible, but most of it ignores a basic archival principle of not altering the artifact in any way. An exception might be a light coat of oil on the steel parts (rubbed on with a rag) to prevent further rusting, but care should be taken not to get oils onto the wooden parts.
I say this with no disrespect to those that choose to restore their guns, but rather to offer the perspective of someone with a background in both history and archival preservation. I consider it my responsibility to curate the guns in my collection as precious artifacts for future generations to enjoy, and I make it my goal to keep them as stable and unchanged as possible. Your mileage may vary.
One other note ... there was a fad in the 1970's to over restore guns, and that has only hurt the value of those guns as the pendulum has swing heavily towards collectors wanting things in "relic condition." Point being, you will almost never go wrong leaving something in its original condition, despite the temptation to do otherwise.
Mike