As noted above, it is possible to buy high quality spring-bars online that are not branded by Omega or any particular watch manufacturer. A decent watch supply house will sell them if you look around. As one might expect, they aren't cheap, but also not $5 each if you buy in quantity. TBH, I've never had a properly installed spring-bar fail (I understand that it does happen, I'm just speaking for myself), so I tend to think that the concern about quality is a bit overstated, but I still buy the expensive ones because it's a small marginal cost.
When fitting a spring-bar, I find it important to focus on the diameter of the tip, which can be more important than the diameter of the bar itself. I like the tip to be snug inside the lug hole if possible, to reduce wear and tear over time from jiggling around. Unfortunately, it's not always easy to know the tip diameter from the sales listing, so you might have to do some trial and error.