I personally think £29 is okay, I think you got the pricing just right, no need to lower it. I think vic charges £39 for permanent regular link in his directory, I charge £30 for one year in Haabaa and £90 for permanent listing, giving the fact that you are constantly promoting this directory, I think the price is okay, don't lower it.
I also believe sensible priced directory tends to keep poor quality sites away. I charge £10 at
www.fx1.co.uk , i get a lot of silly submission, I will be changing the price to £29 next week when I have the time.