It cost me £125 plus vat (£150) for all these tests :
Ishihara colour vision test (1-25 plates of 38-plate test), American Optical Company (H.R.R) Plates (2nd Edition), CAD, Farnsworth D15 Test, City University Test, 2nd Edition, Nagel anomaloscope, Holmes Wright Lantern (type A) and the Holmes Wright Lantern (type B).
Location wise, I'm not too sure...I got the train down from Manchester and then a tube to Angel and its a 5-10 minute walk from there...