Craigslist/fb marketplace can be a good way to find garage sales so you dont have to negotiate a meet up time / place or anything. Also look for estate / moving sales. Check along local roads for signs on upcoming garage sales.
Thrift stores can be ok but can be expensive or not have great stuff if its in an expensive area. Consider going to smaller shops / delis and looking for if they have a section for local business cards; some places will have a section where people will leave a stack of business cards, so you might be able to find smaller thrift/antique shops that way, or find an ad someone has left for upcoming sales.
Also check: local facebook groups, local library in person / website
Not sure about other online sites or specific items though.









For real numbers its 1.2-1.6 g protein per kg bodyweight or 0.5-0.7g per pound of body weight. When i check years back it was something like beyond 0.82g / lbs showed either no additional benefit or diminishing returns. For a 150lbs person that would be 75-105g protein, something like 20% of your daily calories in fat, and then adjust your carbs based on if you want to gain or lose weight