I presume you are going to do carpet cleaning as well. So you will be using the same machine.
There are hot water extraction machines on the market that will do a job for around £1000., and many more costing more then that.
What you looking for (in my opinion) is a machine that has 2 x 3 stage vac motors, and a minimum of 135psi pump.
Take a look at Ashbys, Cleansmart, Prochem, Restormate, Solutions Cornwall, Amtech, Craftex and more that I forgot (but not on purpose).
Also what you looking for is good customer service - and some on the above list are brilliant and some are a bit iffy. Keep reading past posts on here and you will spot who is in what category.