Eh, TP doesnt really have any effect on town shares. Its not like you need 1000 Cowhide to make 1 Sambara share.
The one thing I did notice was the prices jumped up the same time as the tintin/wallace exploit. Seems like a bunch of people who normally do not hold shares got a bunch of fast money and bought off people who normally do.
The thing about people who usually hold shares is they do not sell. To buy shares off someone who hold shares you need to pay a bunch of money to get them to sell. So in one way you overpaid but in another you didnt because they wouldnt sell for less then that.
As long as you dont plan on turning a profit from them its a good deal. You cant put a price on keeping the town you are in secure from people takign it over.