Have experience with about a dozen 45-70s including a Siamese Mauser, multiple Ruger #1s, a Ruger #3, multiple Browning standard 1885s, multiple Browning BPCRs, a Pedersoli 1874 Sharps, a H&R Buffalo Classic and a Thompson Center Encore.
Making your budget range cut off at $1000 permits a few choices.
To get the best value means insuring a rifle that is both accurate, comfortable to shoot and will not depreciate. You also will want to mount good sights and be able to use the best bullets.
Here is a radical concept. The 45-70 is at its best as a single shot round. The 45-70 in a lever gun is not a true 45-70 but is a poor compromise for hunting with lighter bullets.
So you really want a single shot for long range accuracy. And it needs to weigh more than all the light weight toys.
Of the rifles I mentioned above that eliminates all of the light rifles.
The Browning standard model can be purchased used for less than $1000 but it does not have a tang sight option and it is also a little light unless you intend to use a hunting weight rifle.
The heavier Browning 1885 is excellent and comes with very good sights. However it is about $1600 used.
That leaves a nice used Pedersoli which can be found for about $1000.
That will get you a rifle with cheap sights.
If you are happy with adding a scope or using cheap sights on a light rifle you can easily stay within your budget.
For a Real 45 -70 you need a single shot that weighs about 9lbs or more. That will run about $1000 for a good used rifle without quality sights.
You can get a light lever gun or single shot for much less but they are punishing to shoot. You will find very few light 45-70s that have been shot much due to the user hot rodding the round with resulting high recoil. They are good buys if you can resist the need for heavy recoil.
As I stated before I don't consider the lever guns as real 45-70s. They will not handle the most accurate 500 grain bullets.