Medical secretary in private practice in London here. Yes, good cheaper places for cheaper mris are Oryon Imaging and Vista is also ok, I think but haven't used them for some years. I have noticed that some cheap ones in the suburbs near me don't do very good images and don't always have very good radiologists reporting (ie for neurological things you really need a competent neuroradiologist to report the scan, not a general radiologist, etc). The fees vary, depending on what time slot/day you book to get it done - works just like easyjet or ryanair - more popular appointment slots are priced higher like popular flights. Scans are of equal quality and equally comprehensive of that body part regardless of fee paid. All scan centres charge per body part (regardless of size of body part so a toe unlikely to be cheaper than a hand, I believe).