I've purchased pants from both
http://www.calltheobvious.com and
http://www.honigs.com. Some interesting differences:
- Honigs offers pants only in even sizes (e.g., 32" waist, 34", 36", ...)
whereas CallTheObvious has all sizes (e.g., 32", 33", 34", 35", 36", ...)
With no belt, having the right size is valuable. 
- Honigs pants have a black band on the inside. CallTheObvious is white
. Depending on your shape, that can matter. At my age and shape (OK, age doesn't matter), I've had the waistband fold over after I've retrieved something from the floor. Its easy to manage, but I'd rather have it black and not easily noticed. (I know, losing some weight might just avoid the problem. But the issue here is recommendations on buying equipment, not exercise and diet.)
I too have several shirts and choose micromesh/poly according to the weather. Don't buy the cotton-poly combination -- it looks terrible after a few washings. (Little white balls crawling all over you....)
As for how long stuff should last, I think avoiding the dryer will increase the number of cycles your clothes will last. So, have enough to allow them to air dry. I sometimes compromise and use the dryer set to no heat. (There is no chance I can "air them out" to rewear without seeing the washing machine. I couldn't tell if someone was implying that or not....)
Be sure you find black tees with a vee-neck. You need the tee under the shirt, but not the odd stuff at the neck.
Good luck.