I know about them. I have owned about 20 mopeds, including a Pinto. I just love the style of the Pinto frame. Basically the frame was built by Kromag, and the E50 engine is Puch. It is the single speed version. I currently own a 1977 Puch MaxiSport, with the ZA50 2 speed 2 HP engine. I also have a like new E50 engine with 300 miles on it for a replacement if the ZA50 ever blows up. The E50 is a piece of cake to rebuild, the ZA50 can be a real pain because of it's complexity and exacting tolerances. There are tons of Puch parts on eBay, there are also a lot of other places to buy new and used Puch parts (1977 mopeds, Moped Warehouse, Treats, Moped Junkyard, and several more) and Moped Army is the best place to go for information, if you can put up with their somewhat childish behavior.
I won't spend more on a bike than I think it's worth, but if it's a good deal, I don't seem to have a problem buying bikes I don't need.
2002 Vulcan 750, 2013 Royal Enfield B5
2001 XT225, 2009 Genuine Stella
1980 Puch moped