Word of warning: many of those cheap compasses are c-h-e-a-p for a reason. Buyer beware.
I used to work in a large warehouse and we got good laughs during our breaks when we compared the accuracy of many of these cheap asian compasses: they were often 15, 30, even 90-degrees off. Some would actually point south instead of north. In any batch some would be OK, some a little off, some way off, and some, as I said, 180-degrees off.
Just to be clear, I was a navigation specialist and know about the factors, such as nearby ferrous objects, that can effect compasses.
If I were wanted to rely on a compass for my survival, I'd be willing to pay a couple bucks more for quality. Just sayin'