Been lurking for a while thought id contribute.
Bought some Calvin Klein's that i'm pretty impressed with paid about $2 for each pair, but it looks like the store has been taken down.
Got exact same underwear just to test out the 2$ quality and i have to say it is lowest quality possible and not even worth the 2$.
They feel stretchy and elastic but fabric is very thin and they just fell apart after 2nd /3rd wash.
I wouldn't buy it again. Id rather pay a bit extra to get 100% cotton with decent quality.
Also if you wait for discounts i think you can grab gen Ralph Lauren at 15-19$ - for 3-pack.
Having experimented with this niche , I have to say there are two different versions of these boxers at similar prices. Some sellers offer both, I personally prefer the cotton ones and definitely didn't fell apart even after 1-2 years of washing. Links are random, don't specifically suggest these items.
Modal ( stretchy, elastic, thin, like women-like underwear) and
Cotton ( classic cotton, thicker and not so elastic as the above)