M1884s are the most common of the trap door Springfields, and have lower values than some of the other models in equivalent condition. You can find considerable information about them on the internet. Carbines are of far more interest to collectors than rifles, and are priced accordingly. But as is the case for all firearms, originality and condition are the primary drivers of value. It is seldom that one runs across a high condition trapdoor Springfield of any model. I have recently seen some average condition M1884 rifles at gun shows which were priced at around $1000. When I bought mine back in the mid-1980s (at a gun auction), I think I paid around $200 each for them.
To the best of my knowledge, all of the M1884 rifles have the Buffington wind gauge rear sight. I have two of those rifles and shoot them occasionally. They are safe to shoot so long as the cartridges are not heavily loaded. I load my own using Pyrodex, a modern black powder substitute, although light charges of fast burning smokeless powders are certainly OK. Fillers are NOT needed for such light smokeless powder loads. Consult any good reloading manual. There is a lot of reloading data available, as the .45-70 cartridge is still with us and both ammunition and reloading components are readily available. The use of lead bullets only is recommended as the Springfield barrels are made of a fairly soft steel.
Replacement parts are not too difficult to find. The aforementioned Dixie Gun Works (Union City TN) used to carry about every part needed, and I suppose there are also other sources for parts. I have never had a problem with original firing pins, nor am I aware that there even is a firing pin problem. In any event, it is very simple to replace if necessary.
"The shop said it was made in Lancaster PA"
That statement says a great deal about the very low knowledge level of whoever made it.
BTW, if the stock is original, it may have a date stamp on it.