Two things I would be concerned about when buying at "cheap" stores or thrift shops:
(1) Read the fabric content tag (to avoid cotton or rayon) and don't buy if there is no tag.
(2) Hold fleece up to the light. If you can see through it, you don't want it.

Subject to these two tests, you are probably better off than patronizing the high priced gear shops with their "name" (think $$$) brands. Certainly your budget will go a lot farther! You may pay a slight weight penalty on some things.

Check out military surplus stores, too. I'm still wearing a pair of Air Force tropical weight dress pants I bought in 1987 for $5. The fabric is wool and polyester, but it wears like cast iron.