Have you thought of an RDS? I have an older Bushnell Elite 3200 1.5-4.5 with the Firefly reticle on my Marlin 375S. It about killed me to put it on there but it did breath some new life for old eyes. I agree with @
Wyoming Shooter in that it changes the handling of the gun and not for the good either. Since that time I have obtained an AR with an Aimpoint and I'm seriously thinking of just going that route on my lever blaster. Both eyes shooting with no magnification, no eye relief to deal with, putting it where it balances better, less weight, there's just an awful lot to like. I'm beta testing an RDS on my Thompson Center muzzloader this year but I already know it's going to work for me, I've had too much success hitting much farther than 100 yards with a Aimpoint on my AR.
The Vortex Strikefire II would leave a lot of your budget left over.