We are in the process of getting one of such deals. The fee we had was 99.00 and only if the valuation is close to LTV will you be required to pay for the valuation fee. I am not quite sure but I think that you could walk away before paying 99 but after geting their standard valuation.
Our valuation over the phone was 5k more than the most recent sale in our road which was more than enough so we didn't need to pay for the valuation.