It would be better to compare direct substitutes, like tvp vs. ground beef.

The first google results find $3.50/lb for tvp and $6.50/lb ground beef (http://www.nutsonline.com/cookingbaking/beans/soybeans/prote... and http://www.amazon.com/Omaha-Steaks-pkgs-Premium-Ground/dp/B0... respectively).

So the conclusion might be true, despite an invalid argument.