Yes I agree but in all probability the agent would probably agree a £2k fee & only payable on completion or no fee at all. Whereas £200 is lost money with tesco's if you don't sell. I appreciate were looking at x 10 the amount but with this comes a more comprehesive service and the ability to pay out of sale proceeds. In the scheme of things 2k isn't a big deal at such a stressful time of ones life. As an example, many people are currently paying this type of money in redemption fees simply to get a new fixed rate mortgage.
If out of principle you object to paying conventional Estate Agency fees, you will find an alternative in virtually every town. The laws of competitions will dictate that there will always be a cut price EA charging 1% or less with a shop front and internet access. Coupled with a ‘no sale no fee’ policy, why bother paying possible lost money upfront and attempting to do it yourself?