Second hand shopping and discounts are a way to spend less on clothes. Some bargain prices are not worth spending however if the garments falls apart after only a few washes and wears.

How do you know the clothing is of decent quality? What do you look for?

 Thicker fabircs vs the very thin fabrics used in some "bargain" priced clothing, stitching that looks "secure", replacement buttons included. 

My unending quest of find long- lasting quality cotton blend dress socks for dh is leaving me frustrated--found some very nice socks via Lands End but they are $10-$15 per pair!  

That is A LOT to spned for one pair of dress socks.  OTOH, typical dress socks from Target, Penneys, etc. wear through on the heel or toes in less than a year, it seems.  

I check the weight of the material.  If it's too see-through or flimsey, it's not worth it to me. For DD, I get clothes at Children's Place off the clearance rack.  She has worn some of their long sleeved plain t-shirts for month, either alone, or under a short-sleeved tee for a layered look.  They wear well.

I buy most non-undergarments second hand.  I often go for namebrand with tags on if I see them.  Since I live near a college town and near an area with summer homes for the wealthy, I can usually find enough of these to make a reasonable work wardrobe.  Columbia, Lands End, and Eddie Bauer seem to last well for me.  Whether name brand or not, I check for fabric strength, wear, thin spots, tears, stains, and flaws.  I'm willing to restitch a portion of a seam or put on buttons if the rest of the garment is in excellent condition.    Once in a while I miss something...like the Levi's that fell apart in the wash last month!  only a few wearings and the inner-thigh area just dissolved in the washer.  Oh well.  they cost 2.44$

In addition to material weight, I also check the width of the seam allowance.  Cheaper items will often have smaller seam allowances and narrower sewing on the seams - this causes two problems, because narrower seams don't hold up as well, and manufacturers of cheaper clothing often cut material costs by reducing the amount of fabric used in each item, which means cheaper items often run smaller.

I have found some brands generally wear well and will select those over others in thrift stores. I will shop sales and bargain racks at the stores that carry those new.

If I see an article of clothes that has shoddy or uneven stiching, buttons are a little even or anything else like that then I leave it. It's a bad sign to start out that way with a piece of clothes.