TM one pass clean, simples 
My system cost new (everything including van) £40k
Bought second hand after 4 years with 1,200hrs for £15K
Still running perfectly after 8 years of service (2200hrs) and could sell easily for £5k
Some will say, It hardly gets used.... this is true, as a typical day due to it's top notch efficiency, it only run's for an hour or two, doing 2 or 3 jobs a day and uses £3 something per hour on diesel.
I also have to use LM, Porty ect...but my TM pulls rank on these methods every-time!!
I agree with Jim and Mike and I too have trouble understanding Ian's posts, surely the name of the game is to say," yes I can do that for you" (the customer) and charge enough to make a good profit out of each job regardless of how you do it.
Graeme
Similar to what i got, for 20k i got a Mercedes Sprinter 06 with 23k miles on clock,
fully kitted out at Hydramaster by first owner, with a 470 Maxx turbo diesel, with only 62 hours on the clock, fully lined out, with astro turf, HM shelving, various chemicals, 1 wand with a green glide and a stair tool, and an un-used drimaster 2 which i sold to Billy.
Not ran it for a year yet, used scorpion once in that time, dont have access or parking problems, as there is always a way around it, even blocked roads off in quiet areas, and park on double yellows with sign up saying emegancy flood work !!!
Unbelievable power compared to a tripple vac, yes a porty can do same job eventually, but nowhere near the drying times or flushing capabillities.
With regular oil filter changes etc i hope to run it for 20 years, fuel wise i dont know what it costs, my farmer friend supplies me with red diesel as i need it and i clean al his cpts, suites etc as required, even for his staff and family houses, easier than forking out cash !!
Andrew