Simon
thats a lot of money for a few requests.
I am going to stick my head out here. there is no shame in her using the new rug doctors. what carpet cleaners dont see is that the manufactures of these type of machines are direct computation to us. they sell thousands each year and their customers are happy with the results.
Your wife is dealing with customers that spend money on their homes. this means that their carpets will be lightly soiled so any system or method that's suited to these condition will work fine. as the old saying going "no point using sledgehammer to crack a nut" you dont even really need extraction many of the pad systems will work. you are providing a Maintenace service not recovery or restoration. the nice thing about Maintenace is the regular part. this is where you can see if its worth investing that money. I see machines on ebay "like new" from people all the time!
You have to see carpet cleaning from a customer point of view. they are buying a clean carpet not the journey or the pride of the carpet cleaner. as long as that customer feels that you have given them a clean carpet then everyone is happy.
My last point is carpet cleaning is hard work my real recommendation is set up a joint venture with a carpet cleaner that you can trust. pass on the work for a fee. this is free money for you. you have the relationships with the customer that has value and at no cost. the carpet cleaner will want to impress you and your clients so will do a great job for you both.
now you can use that money for a nice holiday
good luck
Ian Harper