... just about everything sold at WalMart is phony ... What did you expect for $10?
A few years back, you could buy a fully functional 3"x5" glass signal mirror from Vector I (a company few had heard of) for not much more than $10.
And I have bought the 2"x3" glass Coghlan's signal mirror (originally OEMed by Vector I) for under $10 - from Walmart, as it turns out.
These days, a good 3"x5" glass signal mirror does cost a bit more - $12.50 is the quantity 100 price from S.I. Howard, the supplier to the US Air Force:
http://flatglassproducts.howardglass.com/viewitems/flat-glass-products-fabrication/signal-mirrors?Survival Resources sells it for $17 (though I dunno what the shipping bite is).