As Ken says,
it depends on how many,what and how you buy(Pa I suspect has no special restrictions like Klaif or NJ which would make it worthless).I will say that once you have one you seem to buy more.
A far as investment,it does not cost much at all and requires some minor bookkeeping that you should be doing anyway if you collect.
Here is another link,
http://p077.ezboard.com/fparallaxscurioandrelicfirearmsforumsfrm72
HTH,
Dave

Hillary For Prison 2018