Old steel Weavers from their made in U.S.A. era are good value. I have several K4s on different guns (including a couple on Lee Enfields) that I picked up secondhand for under $100 and they are still working just as they should. Modern optics have better coatings but that doesn't mean the old stuff got worse, let alone stopped working. (If they do stop working, Trace Scope Repair does excellent work on old Weavers and it's not expensive.)
Personally I wouldn't choose a Leapers or NCStar for half the price, but there are fellows here who report that choice worked for them and I believe them. It's a strategy that can work, try it if you like it.
I also have a couple of modern, alloy, made in Japan Weavers, a K4 and a K6. I like these scopes a lot and wouldn't choose a Leupold over them. To me the extra cost of Leupold isn't justified. I don't disagree with those who say the Leupold product offers better performance, I'll just point out that the law of diminishing returns applies: Leupold can't make fixed 4x twice as good as a Weaver K4 for only twice the cost. It gets harder to get the extra quality, so it costs more. If it's worth it to you, it's worth it to you.
But if you are buying used the extra cost of a Leupold may be worth it because they honour their lifetime warranty on Leupolds sold used. Weaver's lifetime warranty is limited to the original new buyer. (I bought mine used anyway.) From all the positive raving about Leupold's warranty service you should deduce two things: Leupold's warranty service is really good, and even Leupolds break sometimes.
