Would you buy a used car from this dealer at 9404 E. 31st St.?
If memory serves, this same dealer has posted messages accusing those who believe in the enforcement of America's immigration laws of being hateful racists.
Since the signs cost a lot less than $5, maybe people should turn in their signs, then donate the proceeds to buy more signs. :) (I think I saw a variation of that idea on an episode of "The Lucy Show" -- Lucy exploited the double-your-money back guarantee of a brand of canned beans.)
If you'd like a "NO RIVER TAX" sign for your yard, Tulsa Machine (a sign printing shop) at 1503 E. Admiral Pl. has them for sale for a nominal price.