looking for affrodable GPU

Hello, I'm new using Hashcat and my setup has an old 560ti that gives arround 24000 H/s. And I'm thinking in getting another GPU that could give more H/s, as Im still trying dont wanna spend to much, and around 100€ would be mi limit.
would be a 7970 a good purchase? I could buy it for around 50, and also have the chance of getting a 6990 for 70.
or is just better to buy something newer?

thanks.