Nikon glass is generally rated higher than the price point usually indicates. Their M223 line is getting some very good reviews. Just be sure to look at the M series. This uses their Monarch line of optics.
You can go absolutely crazy with optics and there is some justification when performance really matters. However, you need to decide what your use will be and make a decision based on that.
For example, for my .22 upper, I wanted something OK, but not anything budget busting. So I topped it with a fixed 10x Super Sniper. For what I use it for, it's been great.
For a $140 Gamo air gun, I topped it with a $60 Leapers and I'm making one hole groups at 25 meters when I do my job.
I would not want to use either of these in poor conditions. The Leapers has a terrible exit pupil size making quick shots impossible, but then I don't need quick shots with that gun. The image is pretty poor in anything but a nice day, but this gun is for backyard plinking and as such its a fun gun to play with. The Super Sniper has worked much better than I ever expected. The image is bright in every condition I've used it. Eye relief isn't as good as I'd like, but careful positioning and practice has made it very usable.
The point is, decide your needs and buy the tool to meet them. Sure, a US Optics scope is going to be outstanding, but if all you are shooting is your local club's 100-300 yard range on nice sunny days, the extra quality of the US Optics is not going to get you much over a decent Leupold or Nikon.
I'm not saying that you should settle for poor optics. But there is no reason to feel like you are short changing yourself. There are a lot of people making great shots with budget scopes. So long as the optic can hold zero, pass a box test, and provide a good image in the conditions you are most likely to need it, it will do the job.
Do not skimp on mounts. Putting a good optic onto something that can't hold it steady is a complete waste. You can go nuts here and get precision quick mount, or save some $$, and get mounts that are more or less permanent and lap them to make a solid base for the optic.
In the end, it isn't the optic that makes the shot, but the shooter. Saving $1000 to put into ammo so that you can take the gun out to various ranges in various conditions and learning how to make good hits is a much better value. Set your zero, and then keep a notebook with all the adjustments needed to shoot different ranges, wind, or other various conditions.