Hi Ian,
I guess to some extent this is one of those, you get what you pay for situations. Those previously mentioned brands you listed are pretty good ones. The shirt i got from Bass Pro, while i don't remember the exact amount i paid for it, i'm pretty sure i paid in the range of 25 to 35 for it, and the brand is World Wide Sportsman.
Also depends some on the climate you're talking about. If i had brought that W.W.S. shirt to Costa Rica, or on my past trip to Puerto Rico, i would have been sweltering because the shirt doesn't wick at all and isn't breathable enough.
But, for cooler and drier conditions, it would be fine, and i still plan to use for those kinds of conditions–it's an otherwise well made shirt. Just not good for late spring or most of summer here in VA where it can get pretty humid and hot. The more humid and hot it is, the more breathability you want and the more wicking you want. And i want that wicking to be a permanent feature, not a finish that will eventually wear off.
Thanks for the Costco shirt mention. Haven't seen that shirt at my local Costco.
I have these great pants made by Prana (got discounted), made out of 53% Hemp, 44% Recycled Polyester, 3% Lycra and they are thin and very breathable. Wish i could find a light colored LS shirt made out of this material because it's great for hot and humid conditions. Wicks well, dries fast, and doesn't build up too much stink as compared to an all synthetic and non treated fabric (the slight majority of fiber being Hemp helps a lot with that). I've only seen dark colors available for the shirt version, and the shirt version seems to have been discontinued.
Nylon would be a lot tougher and more durable, but the above would stand up to long term UV exposure much better.