I have used the GMAT Club Tests for a while now in the past and I personally believe that the level of questions is very advanced. Once you start solving these questions, you might realize the difficulty of 700+ Level questions and you will be prepared for them.
Considering the prices, I feel such extraordinary level of questions at this pricing is unbeatable. Many companies will offer their set of questions which are good but not at all as advanced as GMAT Club Tests. Make sure you don't complete all the questions during practise sessions, use them to time and give pre-mocks. They are really helpful.