Phil3,
What you're really buying here is a chance at getting a good barrel, from any of the various makers out there. The chances are significantly higher with the better quality barrels, and vastly less with the bargain priced barrels. I've seen some of the lesser quality barrels shoot very well, but those were the exceptions. Lots of run of the mill, and more than a few true "crap" barrels for every one that shot well. When going with one of the top end barrel makers, those odds are reversed. I've gotten the occasional problem barrel from the better barrel makers, but they were the rare exception, the they stood behind them.
It's already been suggested that you go with whatever the best shooters are using, if you want to up the odds of getting a good one, and that's generally pretty good advice. If David Tubb, Norm Houle, Tony Boyer or some other champion shooter is using a particular brand of barrel, there's probably pretty good reason for that. If you notice that none of them are using certain brands, yeah, there's probably pretty good reasons for that, too. The favored brands vary a bit from discipline to discipline, but the general principle remains the same.
The barrels all look pretty much the same, but there's a tremendous amount of differences that go into them, and that's why there's so much difference in price. You mentioned cut barrels, and yes, there's some very good reasons to favor them in many cases. But they're also about the most labor intensive and expensive barrels to produce. Their prices will, of course, reflect that fact. Buttoned barrels are all produced by the same basic process, but again, there's a great deal of differences that go into their production, which you generally can't "see" in the finished product. Was the blank drilled and finish reamed before being buttoned, or was it just drilled and then buttoned? The reaming adds an extra step, but generally produces a better barrel, Again, you can't tell by looking at them, but the differences are there, and will be reflected in the price. Bottom line here, a cheap barrel is almost never a bargain, and you need to match your choice to what you're wanting to do with it. If I'm building an AR to use for general plinking, some casual varminting or that sort of thing, then a cheap buttoned barrel makes perfect sense. However, if I'm building an AR for Service Rifle completion at Perry, you can bet I'll be looking at nothing but good barrels right from the get-go.