I have an laser rangefinder, won it in a hunter's raffle. 6x magnification and supposed to be good to 1K yards, but any reading beyond 300 is pure fantasy. No idea of the cost, but it is certainly cheap.
It's just not something I bother with other than as a toy.
To give you an example. The range at the hunting lease has distance markers out to 500 yards. Laid them myself with a survey tape. None of them can be ranged accurately, with most of the readings falling short. the 500 yard marker if it reads at all, is off by 100 feet.
Just my opinion, but I don't think you are going to get any better data from a cheap laser rangefinder than you would get simply from using a scope with a decent ranging reticle.
Now, if you sink some decent cash into one, maybe things will get better, but that's strictly up to you.