The history of the Sistema pistols has already been covered, So I have nothing more to offer in that respect. But I can offer a few pointers in regards to the collector vs shooter Sistema question:
First is going to be the overall condition. A close second is whether it still has it's original finish and kind of depends on when it was originally made. Also note that in years past, they were modified by the thousands by people after they were imported and you will see many with aftermarket sights and opened ejection ports. Guns so modified are purely shooters and should be priced accordingly.
Original Sistema's will have matching numbers on the frame, slide and barrel. They were issued with matching numbered magazines, but it is rare to find one that still has it's original numbered mag.
A original finish pistol is going to be the most valuable and should command the most money depending on just how much finish is left. After that it is kind of a crap shoot as to desirability.
Also already pointed out they were issued to various branches of the Argentine military and police forces and usually marked as to where they went. Some of the agencies got far less than others and so some of them are far more uncommon than others. The army seems to have gotten the most followed by the navy and then air force. The secret police marked ones seem to be the rarest. They used to be inexpensive but lately they have really jumped in price. Even the Ballester-Molina pistols have taken a steep increase in price.
I can't really tell from the pictures, so I won't hazard a guess as to the originality of the finish, but that one does have the original grips, which is a good sign that it hasn't been messed with. The original finish of the early Sistema's was a brushed blue just like that on Colts made for the US military after 1924. Later on they were parkerized and pistols brought in for refurbishment were parked the same as new production. Lots of them were refinished in Argentina before they were imported to the US.
A quick segue into another interesting little bit of history is that in the entire history only three countries have produced the 1911 under official license. I am fortunate to have examples from all three:
1. Argentina
2. Norway
3. United States.
I have a 1951 Sistema that is original in all respects including the matching number magazine and a 1941 vintage Ballester-Molina that I believe was parkerized by an arsenal in Argentina.