Here's my $.02, just shell out the bux and get an Oehler the first time around. I know they're expensive (I have one), but they're the one that most others are compared to. If you should hit the screens, you don't kill the brains of the thing, just the screens. I've found (the hard and expensive way) that you're almost always better off to spend the money for the good stuff and only cry once, instead of having all kinds of trouble just for the satisfaction of knowing you got it cheaper. Like most other things, I consider my chronograph and investment.
Dirrectly from Oehler is what I recommend. You won't beat their price anywhere unless you find a used one for sale, they are out there too, just not many are willing to part with them.
I had a F1 and a Alpha both and was loosing my mind at their inconsistantcies and high disagreement between each other. I wouldn't recommend them at all even though others claim to have better luck with theirs.
I have an Oehler 43 and a 35P I found used and in near perfect shape. Although setup takes a couple more minutes it is superior measurment equipment without a doubt.
You can get a 35, no printer, two foot rail and two screens to start with for just over 200 bucks if you don't need all the extras and want it compact as possible. It mounts to your tripod and is the only way to got for the budget concious. Consistancy is key, these are consistant units. The third screen is really not needed they are so **** consistant, it is nice though. Good luck.