If you're going to get a chrony, just remember that they work by blocking light. Light variations at different times of the day will cause velocity variations to be reported. So will different types of cloud cover, the worst condition is erratic sunny/cloudy. I used to set up a cover over the one I had and use a light source that plugged into the cigarette lighter on my pick up. At least the readings were consistent enough to be useful.
There are two reasons to use a chrony, they can indicate high pressures that are usually achieved with dangerously above maximum loads and to find a relatively consistent load that is accurate with the components being used. Just because you've achieved a similar velocity that was accurate with one set of components doesn't mean it will be accurate with another of supposedly equal speeds and dimensions. That's why I won't buy part boxes of components either.
The other style of chronograph out there requires you to shoot through screens that electronically register the bullet breaking the screen. These chronographs are expensive and you are constantly replacing screens, they can be used more than once by the way. I personally prefer the screen system, but that just may be old age as the newer stuff may be more reliable although from what I've seen at the range they haven't changed much other than their read out screens.
I finally just quit using one. I really didn't care what the velocity was anymore as long as the load is accurate and predictable at the ranges I will shoot. You should not trust the readings to be very accurate and should actually take out your rifle/pistol and shoot it at all ranges in between the closest and longest distances you feel comfortable with.
Now, this is just my in humble opinion, but I think you are further ahead buying quality loading gear and components or adding the price of the chrony to a decent scope/base/rings than spending it on a chrony that will quickly lose its value.