The one I had 3 years ago cost approx 1500. That may not have been 3T as I wasn't savvy back then!
If you can afford it I would start with a private consult, the big benefit with seeing them privately is the time you get to ask questions. It gave me the chance to ask what the best path for diagnosis was in his opinion (rather than cheapest or what is available on NHS) he stated MRI with some enhancement followed by targeted biopsy if anomalies detected (I had no symptoms or lumpy bits). I think the whole diagnosis cost about 3k as I had the biopsy privately too.