Testing a 20% price rise on new enquiries only

I have four retainer clients and no idea if my INR 18k monthly rate is actually a bargain or just what I said out loud first. So I am not touching existing clients. For the next three enquiries I am quoting 22k, saying it plainly, and then shutting up. I suspect I will lose two of the three and I want to find out whether that bothers me as much as I think it will.