Hi Benjamin,
As others have said, do not accept lengthy tie-ins. It is better if you can get an EA on a 'no sale, no fee' basis. In fact I thought that most of them operated that way these days. Get at least three separate quotes. Try to reach out the more established EA's in your area. Get a couple of them interested. I managed to get mine to agree a fee of 1%, with no tie ins, and on a no sale, no fee basis
Thank you
Bennett