Thrifting fabric is always a gamble for me but I do sometimes find a treasure or two although they have been harder to come by lately as the prices have gone up in the thrift stores as well as everywhere else. A couple of our local stores do have "sales" or mark down prices by a percentage every week or so, but it's not unusual to see men's shirts for $15-$20 so it's not really a great money saver unless a good shirt makes it past week 3 or 4.
A couple of my local stores have dedicated crafty sections that can be quite decently stocked (depending on what has come in, obviously) but most of the fabrics are now being priced around $8-$10/yd (not always yardage) which is pushing it for me, especially as I can't be sure how clean/smell-free it is when it's wrapped in plastic. Some years ago (a year or so into Covid?) it became apparent that that one of the stores had someone's stash (or someone who kept donating from their stash) in their crafty corner. I bought quite a few ziploc bags over the course of about a year and found a lot of the same fabrics kept cropping up - once in a bag of HSTs, once in a collection of narrow strips rolled up like jelly rolls and then some appeared again months later in a bag of random offcuts. Some of those fabrics ended up being the inspiration and foundation for a couple of my favourite scrappy quilts. :-)
Sadly, the quantity and quality of those grab bags has become a bit unpredictable and I've been disappointed to find badly stained or damaged fabrics, and once a chunk of seersucker fabric that made up most of the bag marked "quilting cotton." It may have been cotton but it wasn't very useful to me and there are times when I have wished I had spent my money on fabric that I actually wanted and could use...
I will still keep looking in the thrift stores but I have learned to be a bit more careful about what I buy. :-)