I have had the rails and seats fitted using Colin at
@VWVC (Previously OXFORD T5) at a cost of £5000. He took in part exchange my almost new rubber Kombi floor and triple seat bench at £500 so I paid £4500. He fitted the Caravelle floor at an acceptable level of competence but as he cut and joined bits of old floors (the floors were from twin sliders to fit my single slider) it does not give a factory or one piece floor finish. I have found it to be not great finishing in my opinion resulting in my having to replace the floor at an extra cost of £1200. He did supply two middle seats and a rear bench(bed) in cloth finish in that price and they were all of a good quality (although i plan on having them recovered along with the two front captain chairs to my spec).
So in short , Its not cheap , its not exemplary finishing but this wouldn't stop me recommending him as a competent fitter.