Hi fikey.
For someone not used to buying secondhand binoculars maybe stick to new.
The reason I suggested a new Vortex 20x56 is I think they have a no fault warranty in the U.S., but I am not sure of this.
This may cover collimation issues.
Normally, makers don't cover collimation problems even when the build quality of their binocular is awful.
The lower priced Chinese 15x70 and probably 20x80 have numerous complaints that they don't keep collimation, either new or after a short time.
However, the better Quantam 15x70 in the U.K. seems better made.
The local astro society may be a source of a good Japanese 20x80 from the 1970s or 1980s from a fairly expert seller.
Same with the Soviet/Russian 20x60.
A few of my friends have been using Japanese 15x80s and 20x80s for 45 years almost daily.
It is possible they have dropped them once and had the recollimated, but maybe not.
I used a specially made Soviet 20x60 daily for 15 years until it got out of collimation.
I never had it fixed as I use a Canon 18x50 IS now, but this outside your budget.
If you wear glasses with binoculars then good eye relief is needed.
If you get tired using a scope, have you tried switching eyes or do you have some problems with eye muscles that makes the eyes tired.
My old eyes now have this problem.
If you want a good binocular, then an APM 70mm with different eyepiece sets may be ideal, but much more than your budget.
Do you have a local store that stocks large new or secondhand binoculars?
Regards,
B.