How much time and money should it cost to prepare for CQC

The answer really depends on how much work you do on an ongoing basis to comply with CQC and what system you use to record your actions.

A survey by Pulse reported that practices had spent £10,000 on consultants just to prepare for CQC and cancelling up to 15 consultations on the day of the inspection.

You should have a system that ensures that most information is to hand at all times. You will always get behind in this as you have other daily priorities, but catching up and preparation should not take more than a day or two at the most.
If you have to employ external help, budget for around £500 to £1,000 at the most, which should focus on prioritising issues and a pre-inspection review of what evidence is available and how to address gaps in evidence.

Level of preparedness
Cost of your system
External consultancy
Staff time
Preparing evidence
Stress Level
Totally unprepared £250 to £500 Up to 10,000+ 20 hours 30 hours *****
Reasonably well prepared £250 to £500 Up to £5,000 15 hours 20 hours ****
Mostly prepared £500 to £750 Up to £2,500 10 Hours 15 hours ****
Fully prepared £500 to £1,000 None None 10 hours ***
everythingCQC
Evidence System
£600 pa None None 2-3 hours **