If there is concern about one particular aspect of the 11+ results such as NVR, it might be possible to limit the cost of an EP report considerably by asking if just this one area could be tested (using the British Ability Scales NVR tests, for example). It may not be easy to find an EP willing to do this, however, as most will probably want to give the full battery of tests!
Failing that, I'm afraid your friend will have to rely on whatever evidence is available.
The more outstanding that evidence is, the better!
If the school is full after the allocations, or might become oversubscribed as a result of appeals, don't overlook the need to give good reasons for wanting a place at the particular school being appealed for: http://www.elevenplusexams.co.uk/appeal ... -school#c2