Its tough to find and afford a pre-64. I searched for a few years and finally got one reasonably priced in great shape made in 1961, most I saw in this condition were $700+, I didnt pay even close to that. I was pretty happy but when it comes to hunting, my Marlin 336c is what I turn to. Not to say that the Model 94 isn't great, especially the pre-64 or pre-safety models, but my Marlin does everything the Winchester does, its brand new, cheaper and replaceable if I screw it up. Plus a good used one after deer season will run you $300 or so. Brand new $450(336c) or $400(336w) depending on which model you go with. They have some pretty serious history too btw and can be scoped easier if you are into that sorta thing. Just an idea.
But as far as what to look for, start with the serial number that has already been mentioned. The pre-64' do look and feel better to me, my brother's 94 was made in the 80's and it shoots exactly the same as mine, just feels a bit "cheaper". His was priced like a used Marlin.
So I started off just like you, I wanted a Model 94 just to have one and I insisted it be a pre-64. Then after I got it I thought it was too nice for anything other than walking to the deer stand with. Hence the Marlin purchase as my workhorse levergun. My Model 94mostly sits in the stable lookin good. And to be honest, I really like my 2 Levergun system right now.