Low cost Technical shirts

I have several of the sleeveless and long sleeve target shirts. I mostly use them for running and working out. I've never had any problems with them and they're a great value if you don't want to spend 30+ on a shirt. They also have thicker "midweight" ones, some with mock necks. I have those too, they have a softer, fleecier inside. I find I like those more than say, the rei polartec midweight base shirts.

With that said, I wouldn't replace my patagonia cap 1 silkweight stretch LS or icebreaker body fit 150/200 with the C9's any time soon. Cap 1 silk weight stretch is great for summer, its UPF 50, so you don't need to bring so much sunscreen since your arms are covered. I got mine for <25 on sac and rock creek.

Y'know, there are some excellent clothes out there if you are observant. Every once in a while a big-box design team will get it all done right and you'll find a great piece of gear. You can get some turkeys too, but then you aren't paying $125 for a polyester hoodie this way.

I've seen lots of very useable clothing with brands like Champion, JC Penney, Destination 10,000 Feet, Adidas, Reebok, Lands End, and so on. Some might be less breathable, or the zippered and seam work might not be up to the big guys. It may all be a touch heavier, but not much. It can mean the difference in getting out, and allows you to save a little to put towards more critical gear like the Big 3.

What is important to know is the theories and techniques of layering and wicking fabrics. With those tools in hand, you can walk into Ché Targét or Ross and put together a perfectly warm, dry layering system for small percentages of what a trip to REI or the Patagonia store would cost. I can do the same in a thrift store and walk out with a layered clothing set that costs about the same as a new trail guide book.

Clothing is highly over-rated by many.
More of a status thing, than really necessary.
I like using high quality gear that does the job.
I dont find that my shirt, underwear, pants, or even socks make much of a difference.
Same can be said for fleece. Old Navy does the job just like Patagonia.
There might be minor niceties on the expensive items, but they arent necessities.