hey Tim and welcome
vintage will almost always give more bang for buck
4/8 5/8 6/8 7/8 is parts of an inch (the widt of the blade)
i would suggest starting at 5/8 size
gold dollars is cheap good steel but may be a bit big to start with
entry level dovo is not much different from the expensive ones
any shave ready vintage from the classefieds should be good too

look around and ask questions if you see something you like but are not sure