I bought my "no-name" manual pistol grip type at WalMart many years ago. Still works fine after all these years. I added the longer hose onto it when I first bought it and am still using the same connector it came with. The only hang up is sometimes, depending on the angle I am at and how much pressure to get grease flowing the pistol grip is tough to use. In those situations A lever action would be better but I cannot justify having 2 grease guns at this point.
I have considered the electric/battery models to overcome that same issue but given their price and lack of a manual backup should the battery fail....